This investigation deals with the effect of chlorpromazine, on Uromastix hypophyseal prolactin. Administration of the doses 0.125, 0.25, 0.5 and 1 mg chlorpromazine per 3 days per animal resulted in a significant increase pigeon crop-sac response (p<0.01). The degree of proliferation of crop-gland showed a dose dependent threshold. Chlorpromazine binds to the target cell specific receptors of PRL and GH, both at the same time.