Bhakuni and Dhar (1968) reported isolation of a new pro-aporphine base, crotsparine, from the extracts of whole plant of Croton sparsi florus Morong. They also reported the conversion of crotsparine. to N-methyl crotsparine which could be further converted into apo-N-methyl crotsparine. All these substances were subjected to pharmacological testing and the preliminary results are being reported here. Crotsparine when administered intravenously to anaesthetised (pentobarbitone, 35.0 mg/kg i.p.) cats produced a transient pressor response (20 - 30mm Hg) in low dose (5.0 mg/kg) and a depressor response (40-50 mm Hg) in high dose (10-25 mg/kg) for 40 to 60 min. Pressor response to adrenaline (1 to 2(g) was, however, reversed for 30 to 40 min by all the doses employed. The compound had no significant effect on the depressor responses to acetylcholine and histamine and on the response of the nictitating membrane to electrical stimulation of its Preganglionic sympathetic nerve.