第 4 季 共 13 集
播出时间：2000年9月17日
第 1 集 The Musical Chairs Syndrome
播出时间：2000年9月17日
Changes abound at MIB as Dr. Zeeltor takes over in the lab for Elle, who has become a field agent and gotten partnered with an alien named Agent X. As these new changes set in, MIB has to stop New York from being devoured by a Barooga.
第 2 集 The Spectacle Syndrome
播出时间：2000年9月24日
Jay and Kay have to rescue the worms from an alien world similar to Ancient Rome.
第 3 集 The Back to School Syndrome
播出时间：2000年10月1日
Jay poses as a high school student to protect an alien prince from alien terrorists.
第 4 集 The Opening Gambit Syndrome
播出时间：2000年10月8日
Thirty years ago, an Ixion named Vangus came to Earth and was stopped by an MIB agent. Now when Vangus returns, MIB seeks answers from the agent that stopped him: Alpha.
第 5 集 The Future's So Bright Syndrome
播出时间：2000年10月22日
During pursuit of a large criminal Worm, Jay gets sent to the future and finds that the Worms rule all of Earth.
第 6 集 The Loose Ball Foul Syndrome
播出时间：2001年4月15日
The Fmeks are back and trying to take over a tiny planet that resembles a baseball. To make matters worse, Kay is on the tiny planet and things are getting very hot.
第 7 集 The Hots for Jay Syndrome
播出时间：2001年4月22日
After eating some alien food, Jay gains the ability to throw fire. But this new power will have serious consequences if he keeps using it.
第 8 集 The Circus Parade Syndrome
播出时间：2001年4月29日
A member of a witness protection program for aliens is on the run from an intergalatic gang called The Association when they discover he's on Earth.
第 9 集 The Virtual Crossfire Syndrome
播出时间：2001年5月6日
Jay gets a low score on MIB's new virtual reality training test and the embarassment eventually forces him to try again. But this time the game goes haywire and the dangers Jay faces become deadly.
第 10 集 The Breaking News Syndrome
播出时间：2001年5月13日
An alien tv crew comes to Earth to film MIB agents on the job just as Drekk returns to cause trouble.
第 11 集 The Zero to Superhero Syndrome
播出时间：2001年5月27日
A super hero caling himself Cosmosis emerges to defend the city from evil, but he's really an alien looking to put his powers to good use. However, MIB feels his new profession could attract trouble for Earth, so they try to lure him out using Jay as bait.
第 12 集 The Endgame Syndrome, Part 1
播出时间：2001年6月24日
Alpha, Vangus and the Ixions return to Earth, working together to threaten all life on the planet. With invasion imminent, Zed decides to reveal MIB's existence to the world.
第 13 集 The Endgame Syndrome, Part 2
播出时间：2001年7月1日
With MIB having success in coordinating resistance against the invasion, the Ixions plan to unleash a weapon that will kill everyone on Earth. Jay and Kay will fight Alpha in the final battle for humanity.
