This paper investigates the laxative effect and acute toxicity of certain fractions of senna extracts in mice. The same tests were also carried out with several pure anthraquinone derivatives common in senna pods. The results show that the laxative and toxic components of senna pods and senna extracts can be separated. The most potent laxative components, sennosides A + B and Fraction V (relative potencies 1 and 0.9 respectively), have the lowest toxicity (relative intravenous toxicities 1 and less than 1). Fractions with very low laxative activity (rhein-8-glucoside and Fraction IV, relative potencies 0.56 and 0.05) have the highest acute toxicity (relative toxicities 10 and 32 respectively).