Abstract 1. 1. High-speed supernatant fractions from tissue homogenates of eight species of insects representing four major orders were tested for sulphotransferase and phosphotransferase activities. 2. 2. A sulphotransferase system was present in all the species tested and required ATP, Mg 2+ and inorganic sulphate for the sulphation of p -nitrophenol, dehydroepiandrosterone and 22,25-bisdeoxyecdysone. 3. 3. A phosphotransferase which in the presence of ATP and Mg 2+ catalyzed the phosphorylation of p -nitrophenol was present in the Madagascar cockroach and in some of the other species investigated.