Josamycin propionate, a tasteless josamycin derivative suitable for the preparation of paediatric oral suspension, was employed in a large, multicentre clinical study aimed at evaluating the effectiveness and safety of the drug. Two hundred paediatric practitioners participated in the study, and 1908 children (mean age 5.27 years) were treated. Respiratory and pararespiratory infections were the most common diagnosis. The mean daily dose of josamycin was 53.5 mg/kg and the drug was administered for an average of 7.31 days. Josamycin proved to be a highly effective antimicrobial agent for the treatment of infections occurring in paediatric practice, with a success rate of 97.1%. The drug also showed a high degree of acceptance by the young patients and was very well tolerated: only 98 children (5.14%) developed side-effects during the treatment. However, the side-effects observed were reliably attributable to josamycin in only 10 out of 300 subjects who were not receiving other drugs; among these the frequency rate was 3.33%.