Rick Moranis as Wayne Szalinski

Matt Frewer as Big Russ Thompson

Marcia Strassman as Diane Szalinski

Kristine Sutherland as Mae Thompson

Thomas Wilson Brown as Little Russ Thompson

Jared Rushton as Ronald Thompson

Amy O'Neill as Amy Szalinski

Robert Oliveri as Nick Szalinski

Carl Steven as Tommy Pervis

Mark L. Taylor as Don Forrester

Kimmy Robertson as Gloria Forrester

Lou Cutell as Dr. Brainard

Craig Richard Nelson as Professor Frederickson

Laura Waterbury as Female Cop

Trevor Galtress as Male Cop

Martin Aylett as Harold Boorstein

Janet Sunderland as Lauren Boorstein

Frank Welker as Special Vocal Effects (Voice)

Patrick Brown as Employee (uncredited)

Isabel del Puerto as Women (uncredited)

Sammy as Quark the Dog (uncredited)