In order to compare the clinical efficacy and safety of TMS-19-Q.GC tablet (TMS) with josamycin tablet (JM) in acute tonsillitis, the double blind trial was carried out with the daily dosage of 200 mg X 3 in TMS and 400 mg X 3 in JM. Number of cases evaluated for clinical efficacy were 154 cases (73 treated with TMS and 81 treated with JM). The effective rating of TMS and JM were 89.0% and 88.9% judged by doctors in charge, and 82.2% and 85.2% judged by committee respectively. Bacteriological effects were satisfactory to yield the eradication rates of 93.8% in TMS and 94.7% in JM. Number of cases evaluated for safety were 199 cases (101 treated with TMS and 98 treated with JM). The incidence of side effect was 4.0% (4/101) in TMS and 5.1% (5/98) in JM and most of them were mild gastro-intestinal disorders. Number of cases evaluated for utility were 156 cases (74 treated with TMS and 82 treated with JM). The usefulness rates were 85.1% in TMS and 86.6% in JM. There was no significant difference between TMS and JM, in clinical effect, bacteriological effect, safety and utility. From these results, daily 600 mg dosage of TMS was as useful as daily 1,200 mg dosage of JM in the treatment for acute tonsillitis.