1. A study was carried out to determine the kinetics of the gastric absorption of two wide spectrum benzimidazole anthelmintics, albendazole and mebendazole. 2. The method used was gastric recirculation of solutions containing the drugs in concentrations ranging from 0.5 to 100 mM. 3. The results obtained showed that absorption corresponds to first order kinetics, with diffusion constants of 0.0087 min-1 for albendazole and 0.0077 min-1 for mebendazole. 4. Blood levels of the drugs for the whole range of concentrations were always higher in the case of albendazole.