Effect of food deprivation on bar pressing for light onset was examined as a function of inclusion of unconditioned operant pretest sessions. Two groups of 6 albino rats were given 9 30-min. sessions, which depression of 1 of 2 levers led to light onset; 2 groups of 6 rats were given 3 30-min. sessions under unconditioned operant conditions, followed by 9 30-min. onset sessions. In each case 1 group was 22-hr. food deprived, the other satiated. Food-deprived Ss showed a higher rate of bar pressing on the onset lever than food satiated when run following unconditioned operant pretests (p < 0.1), but not when run under onset conditions only.