On of the most important factors in the generation of schedule induced polydipsia, and schedule induced self‐injection of drugs is the prior reduction of the animals' body weight to 80% of their free‐feeding weight by food deprivation. It is suggested that reductio of body weight to 80% by water deprivation should produce similar results. The series of experiments reported here showed that rats reduced to 80% body weight by water deprivation did not develop either schedule‐induced polydipsia or schedule induced wheelrunning. The results thus suggest that body weight reduction may not be a critical condition in the development of schedule‐induced phe