Neil Patrick Harris

as Doogie Howser

Max Casella

as Vinnie Delpino

James Sikking

as Dr. David Howser

Belinda Montgomery

as Katherine O'Brien Howser

Kathryn Layng

as Nurse Mary Margaret "Curly" Spaulding

Lawrence Pressman

as Dr. Benjamin Canfield

Lucy Boryer

as Janine Stewart

Markus Redmond

as Raymond Alexander

Mitchell Anderson

as Dr. Jack McGuire

Lisa Dean Ryan

as Wanda Plenn