How Much Did NCIS Viewership Really Drop After Mark Harmon's Exit?

For the past couple of decades, fans' utter devotion to CBS' long-running military procedural "NCIS" has helped make it one of the jewels of the network's primetime scheduling slate. The series has naturally changed a bit since its 2003 debut, as has the number of fans who tune in to watch the crack team of Naval detectives from one week to the next. And it should come as no particular surprise that the exit of longtime "NCIS" star Mark Harmon may have had a dramatic impact on the series' ratings.

Harmon's "NCIS" exit came early during the series' 19th season. While he was hardly the first star to walk away from the show, he was undoubtedly the biggest, with his Leroy Jethro Gibbs running point on the NCIS team from the moment the show hit the air. Harmon's final "NCIS" episode ran in October 2021, with the always amazing Gary Cole stepping in to fill the void as Supervisory Special Agent Alden Parker for the duration of Season 19. Ratings reportedly held relatively steady thereafter, though the same could not be said for the Season 20 premiere of NCIS," which earned the lowest ratings in series' history.

That season opener was a full-on crossover event with "Hawaii 5-0," so the ratings debacle doesn't fall squarely on the shoulders of the "NCIS" crew. And it should be noted that "NCIS" rebounded nicely as Season 20 unfolded. 

It's safe to assume a ratings dip was more-or-less expected for "NCIS" after Mark Harmon's exit, as viewers historically waver when a beloved star walks away from a show years after its launch. Surprisingly, the first episode after Harmon's exit actually saw an uptick in the ratings. Perhaps even more surprising is that ratings were reportedly down for Harmon's final episode, as the swan song of Leroy Jethro Gibbs turned in season lows on the ratings front.

Of course, those numbers were still enough for "NCIS" to claim the top spot in its Monday night time slot. And yes, the show has remained a force to be reckoned with in that same Monday night time slot ever since — so much so that CBS didn't blink at renewing the show for its 21st season. As for the transition from Harmon to Cole, "NCIS" creatives handled the delicate transfer of power with admirable dexterity.

Said transition begins in Episode 2 of Season 19, with Parker taking over the big job after Gibbs is suspended. When Gibbs sets off for Alaska with his protege Timothy McGee (Sean Murray) in tow to run down a serial killer, Parker eventually steps in to help close the case and clear his predecessor of any wrongdoing. Gibbs and McGee share a goodbye befitting their father-son like relationship just before the credits roll. And if you've seen those final moments between the "NCIS" fan favorites, you know they made for an exit that will not soon be forgotten.