Juliflorine (CAS 76202-00-1), an antibacterial and antidermatophytic alkaloid, was studied for its toxicity in mice, rabbits, chicks, chick embryos and vero cell line. In mice LD50 was determined as 17.46 mg/kg; in rabbits 33.11 mg/kg; in chicks 24.104 mg/kg; and in chick embryos 18.284 mg/kg. In rabbits the subsequent injection of non-lethal doses (10 mg/kg) through the same route induced swelling, induration, inflammation and tissue degeneration (around injected area) with sterile abcess. Topically 1% juliflorine in polyethylene glycol-400 was found non-toxic but higher concentrations (less than or equal to 2.5%) produced irritation and inflammation; the severity of reaction was dose dependent. In vero cell-line juliflorine was found toxic at greater than or equal to 5 micrograms/ml. Injected animals showed lethargy, prostration and weakness (dose dependent) but recovered after some days, while newly hatched chicks, from injected eggs with higher dose, did not survive after 48 to 72 h. Internal organs (liver, kidney, brain, etc.) of dead, sick and healthy animals were examined and found normal.