Hey Arnold! - Season 4
1 - Full Moon
Air Date: March 10, 1999
Harold, Sid, and Stinky all moon Principal Wartz, but Arnold is blamed, even though he was just an innocent bystander.
2 - Student Teacher
Air Date: March 10, 1999
Helga's sister Olga comes home for spring break and becomes a classroom aid in Helga's class, much to Helga's chagrin.
3 - Big Gino
Air Date: March 15, 1999
After Sid works off a debt with loan shark Big Gino, the two become friends, but when Sid is told to give Arnold a swirlie, he has to choose between the two.
4 - Jamie O in Love
Air Date: March 15, 1999
Gerald's older brother Jamie O has a sudden burst of kindness when he finds a girlfriend, but Arnold and Gerald soon find out that the girl is just using Jamie O.
5 - Eugene's Birthday
Air Date: March 17, 1999
After losing Eugene's birthday party invitations, Arnold feels obliged to throw him another party, but it doesn't work out.
6 - Stinky's Pumpkin
Air Date: March 17, 1999
Stinky grows a huge pumpkin to enter in a city competition.
7 - The Beeper Queen
Air Date: March 29, 1999
After Bob pops his spine, Miriam runs Big Bob's Beepers. She gets in over her head and forgets about her family.
8 - Oskar Can't Read?
Air Date: March 29, 1999
Arnold finds out that Oskar is illiterate and tries to teach him to read.
9 - Dinner for Four
Air Date: March 31, 1999
Helga wants to show Arnold that she can be as sophisticated as Lila is by taking him, Gerald, and Phoebe out to dinner with a coupon she won. She devises a plan to get out of paying when she discovers they're at the wrong restaurant.
10 - Phoebe Skips
Air Date: March 31, 1999
Phoebe is promoted to the sixth grade, but realizes that her new so-called "friends" are just using her to do their homework.
11 - Helga's Parrot
Air Date: April 5, 1999
A sleep-talking Helga confides into Bob's parrot about her love for Arnold. The next day, the parrot flies into Arnold's window, and it is up to Helga to get it.
12 - Chocolate Turtles
Air Date: April 5, 1999
Crisis strikes when Gerald's little sister, Timberly, eats a stock of chocolate turtles that he and Arnold are supposed to sell for a local scout organization.
13 - Love and Cheese
Air Date: April 7, 1999
Helga tries to separate Arnold from Lila while at the annual Cheese Fair.
14 - Weighing Harold
Air Date: April 7, 1999
Harold, after discovering his friends think he is obese, decides to go on a weight-loss cruise. When he comes back, though, he is noticeably larger.
15 - Back to School
Air Date: September 11, 1999
After Grandpa tells Arnold that he never got his grade school diploma, Arnold convinces him to come to go back to school at P.S. 118.
16 - Egg Story
Air Date: September 11, 1999
Arnold and Helga must care for an egg for a school project about parenting. Meanwhile, Rhonda and Harold are project partners and must also take care of an egg.
17 - It Girl
Air Date: September 18, 1999
Helga becomes a model, but she quits after she gets irritated at everyone dressing like her.
18 - Deconstructing Arnold
Air Date: September 18, 1999
Arnold's classmates are tired of constantly telling them the right thing to do, so he stops giving them advice. Nevertheless, when his classmates get into sticky situations, they are in desperate need of his advice.
19 - Grudge Match
Air Date: September 25, 1999
After getting in a car accident, Bob and Grandpa face off on the golf green, with the loser having to pay for the damage to both cars.
20 - Polishing Rhonda
Air Date: September 25, 1999
Rhonda attends a finishing school, but is far from impressive with her stroppy attitude, and seeks help from fellow student Big Patty.
21 - Weird Cousin
Air Date: October 9, 1999
Arnold's bland country cousin, Arnie, comes to visit. Arnold begins to notice that Arnie and Lila show interest in each other, making him jealous.
22 - Baby Oskar
Air Date: October 9, 1999
Oskar has to take care of his infant cousin-in-law (also named Oskar), while both Susie and her cousin are gone.
23 - Grandpa's Sister
Air Date: October 16, 1999
Phil's twin sister comes for a visit, bringing along an unsettled conflict between them.
24 - Synchronized Swimming
Air Date: October 16, 1999
Arnold and the gang are part of a synchronized swimming team led by Coach Wittenburg.
25 - Helga Sleepwalks
Air Date: October 23, 1999
After eating pork rinds, Helga sleepwalks, uttering her secret about Arnold as she does so.
26 - Fighting Families
Air Date: October 23, 1999
Arnold, Grandpa, Grandma, Ernie, and Mr. Hyunh compete on a game show against a "perfect" family from PS 119
27 - Headless Cabbie
Air Date: October 30, 1999
Arnold tells an urban legend about a decapitated taxi driver. The gang goes out, only to find the details in the story are becoming real.
28 - Friday the 13th
Air Date: October 30, 1999
Arnold and Gerald try to prove superstitions are fictitious, only for it all to backfire on them.
29 - Veterans Day
Air Date: November 6, 1999
Arnold's Grandpa recalls his adventures as a soldier in the Second World War, outwitting a regiment of Nazis, while Gerald's dad, Martin, remembers his own time serving in Vietnam.
30 - Helga on the Couch
Air Date: December 4, 1999
Helga confides in the school psychiatrist about her social life, family life, and her love for Arnold.
31 - Dino Checks Out
Air Date: December 11, 1999
Dino Spumoni is found missing and then declared dead after what appears to be a suicide attempt. but Arnold finds out that this isn't the case, and he secretly lives in the boarding house, believing that his work will skyrocket in value after his "death".