

The episode received four nominations at the 50th Primetime Emmy Awards, winning one. Praise was given to the live performances but the story and script writing was criticized being lackluster. Reception to the episode was mixed from critics. Watched in a total of 42.71 million viewers, the episode became the most watched season premiere episode for a drama series. In its initial airing, "Ambush" received the highest rating of the week, in front of episodes from Seinfeld and Veronica's Closet.

Inspiration for the episode came from production staffers having worked in documentaries, with Anthony Edwards and George Clooney suggesting to do it live. The episode introduced British actress Alex Kingston as Elizabeth Corday to the cast. Shown through the perspective of a PBS documentary film crew, the emergency room is filmed as a day in the life of the doctors. Written by executive producer Carol Flint and director Thomas Schlamme, the episode was first broadcast on NBC on September 25, 1997, as a live episode, filmed twice for the east and west coast. " Ambush" is the premiere episode of the fourth season of the American medical drama ER.
