Clinical effectiveness of TMS-19-Q, a new macrolide antibiotic, was evaluated in superficial infectious diseases classified into 6 groups at 13 departments of dermatology. The results obtained were as follows: Final global improvement rating in 311 cases were excellent in 91, good in 158, fair in 45 and poor in 17 and the effective rate was 80.1%. Effective rates in each group were 71.1% in 1st group (folliculitis and acne pustulosa), 78.6% in 2nd group (furuncle, furunculosis and carbuncle), 100% in 3rd group (impetigo), 76.9% in 4th group (phlegmone, superficial lymphangitis, erysipelas and infectious paronychia), 88.7% in 5th group (inflammatory atheroma, subcutaneous abscess, hidradenitis suppurative and acne conglobata) and 77.3% in 6th group (secondary infection). Dominant strains isolated were S. aureus (40.7%), S. epidermidis (26.9%) and anaerobic bacteria (20.8%). S. aureus was frequently isolated from most of all disease. On the other hand, S. epidermidis and anaerobic bacteria were isolated mainly from 1st and 5th group. Optimum daily doses would be over 600 mg. Slight adverse reactions such as gastrointestinal disorders, eruption and malaise were observed in 12 cases.