Twenty-six individuals infected with Taenia saginata, 18 males and eight females ranging in age from 19-46 years, were treated successfully by a single oral dose of praziquantel at 10 mg kg-1 body weight. The drug was well tolerated, and no appreciable side effects were observed. Of the 26 patients, eight harboured one worm and the remainder harboured two or more worms; eight worms were obtained from one individual. In all 75 worms were recovered, ranging in length from 1.05-4.55 m, with a mean length of 2.26 +/- 0.36 m. The number of segments per worm ranged from 283-758, with a mean of 450 +/- 57.6. The mean wet and dry weights of the worms were found to be 26.1 +/- 2.7 g and 4.00 +/- 0.32 g respectively. The mean length of the worms, the mean number of segments per worm and the mean wet and dry weights were observed to decrease significantly (P less than 0.01) with an increase in the number of worms harboured by the patient.