* William Devane as David
* Helen Mirren as Jill
* Jamie Lee Curtis as Jennifer (credited as Jamie Curtis)
* Joey Heatherton as Tina
* Don Stroud as Tom
* G.D. Spradlin as Sheriff
* Richard Dawson as Sheriff's Deputy
* Tom Bosley as Father (uncredited)
* David Canary as Father (uncredited)
It's worth noting that Jamie Lee Curtis, who would later become famous for her roles in horror films like "Halloween", makes her film debut in "Grasshopper Island" at the young age of 12.