Abstract: The total alkaloids (AC-445), isolated with alcohol from Narcissus tazetta L. var. chinensis Roem collected from Changchou city of China, were prepared at our Institute. This paper deals with its antitumour activity and toxicity. 1. AC-445 could inhibit significantly the tumour growth of the Jensen sarcoma in rats, and the Crocker sarcoma and Ehrlich ascites carcinoma in mice. 2. In mice, the acute intraperitoneal LD₅₀ was found to be 182 mg/kg. The suba- cute LD₅₀ after 10 intraperitoneal injections of AC-445 for mice and for rats were 59 and 23 mg/kg/day respectively. 3. AC-445 might cause emesis in dogs until after 2-3 injections. At the dose levels of 16 mg/kg or below, AC-445 might produce a leucocytosis for about a month.