Hey Arnold! — Season 4
01 Full Moon
Mar 10, 199911m★ 6.5
Harold, Sid, and Stinky all moon Principal Wartz, but Arnold is blamed, even though he was just an innocent bystander.
02 Student Teacher
Mar 10, 199911m★ 6.5
Helga's sister Olga comes home for spring break and becomes a classroom aid in Helga's class, much to Helga's chagrin.
03 Big Gino
Mar 15, 199911m★ 6.0
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.
04 Jamie O in Love
Mar 15, 199911m★ 6.0
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.
05 Eugene's Birthday
Mar 17, 199911m★ 6.0
After losing Eugene's birthday party invitations, Arnold feels obliged to throw him another party, but it doesn't work out.
06 Stinky's Pumpkin
Mar 17, 199911m★ 7.0
Stinky grows a huge pumpkin to enter in a city competition.
07 The Beeper Queen
Mar 29, 199911m★ 8.0
After Bob pops his spine, Miriam runs Big Bob's Beepers. She gets in over her head and forgets about her family.
08 Oskar Can't Read?
Mar 29, 199911m★ 7.5
Arnold finds out that Oskar is illiterate and tries to teach him to read.
09 Dinner for Four
Mar 31, 199911m★ 7.5
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
Mar 31, 199911m★ 7.0
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
Apr 5, 199911m★ 6.0
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
Apr 5, 199911m★ 6.0
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
Apr 7, 199911m★ 7.0
Helga tries to separate Arnold from Lila while at the annual Cheese Fair.
14 Weighing Harold
Apr 7, 199911m★ 7.0
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
Sep 11, 199911m★ 7.0
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
Sep 11, 199911m★ 7.0
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
Sep 18, 199911m★ 6.0
Helga becomes a model, but she quits after she gets irritated at everyone dressing like her.
18 Deconstructing Arnold
Sep 18, 199911m★ 7.0
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
Sep 25, 199911m
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
Sep 25, 199911m
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
Oct 9, 199911m★ 8.0
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
Oct 9, 199911m★ 6.0
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
Oct 16, 199911m★ 7.0
Phil's twin sister comes for a visit, bringing along an unsettled conflict between them.
24 Synchronized Swimming
Oct 16, 199911m★ 8.5
Arnold and the gang are part of a synchronized swimming team led by Coach Wittenburg.
25 Helga Sleepwalks
Oct 23, 199911m★ 7.0
After eating pork rinds, Helga sleepwalks, uttering her secret about Arnold as she does so.
26 Fighting Families
Oct 23, 199911m★ 7.0
Arnold, Grandpa, Grandma, Ernie, and Mr. Hyunh compete on a game show against a "perfect" family from PS 119
27 Headless Cabbie
Oct 30, 199911m★ 7.0
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
Oct 30, 199911m★ 8.0
Arnold and Gerald try to prove superstitions are fictitious, only for it all to backfire on them.
29 Veterans Day
Nov 6, 199923m★ 8.0
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
Dec 4, 199923m★ 8.0
Helga confides in the school psychiatrist about her social life, family life, and her love for Arnold.
31 Dino Checks Out
Dec 11, 199923m★ 8.0
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".