The acute toxicity of taxine isolated from leaves of yew trees was determined in mice and rats. The drug was used as the sulphate salt. The following LD50 values (mg/kg) and 95% confidence limits were found: mice po 19.72 (16.84-23.09); mice ip 21.88 (19.66-24.35); rats sc 20.18 (18.35-22.20).