Clinical efficacies of a new macrolide antibiotic, rokitamycin (RKM, TMS-19-Q), were studied in acute pediatric infections. Responses to the RKM administration were evaluable in 62 out of 68 patients consisted of 7 patients with pharyngitis (efficacy rate of 85.7%, 6/7 patients), 4 with bronchitis (25.0%, 1/4), 9 with tonsillitis (100%, 9/9), 13 with mycoplasmal pneumonia (100%, 13/13), 13 with hemolytic streptococcal infections (92.3%, 12/13), 14 with pneumonia (57.1%, 8/14), one with pertussis (100%, 1/1) and another with Chlamydia pneumonia (100%, 1/1) thus an overall efficacy rate of 82.3% was achieved. Urticaria was observed in one of the patients as an adverse reaction to the drug, while abnormal laboratory test results were noted in 3 patients, but none of such changes were severe. The drug, even when administered in combination with a theophylline preparation, exerted no effects on the serum concentration of the latter.