This ether oxim derivative of erythromycin A is an easy to absorb oral antimicrobial somewhat less effective in vitro than erythromycin. At relatively low MIC's it is active against staphylococci, streptococci, pneumococci, branhnamella and chlamydiae, higher concentrations are needed against enterococci and some strains of H. influenzae. Roxithromycin is also reported to have a very good effect on campylobacters, many anaerobic bacteria, Toxoplasma gondii, Treponema pallidum, Mycoplasma pneumoniae and Legionella pneumophilla. Its half-life in the serum of healthy individuals ranges from 9 to 16 hours. Maximum serum concentrations at 2 oral doses of 150 mg a day are reached at 3 to 4 days and vary from 5.5 to 11.1 mg/l. The distribution of roxithromycin in body tissues is excellent. In a group of 57 patients treated for various infections of clear etiology the positive therapeutic effects resulting in the state of bacteriological negativity was reached in 86% of cases. Roxithromycin can be recommended as a drug of choice in mild or less severe cases of infection caused by agents sensitive to this antimicrobial. Its excellent tolerance makes it especially well suited for use in pediatric practice.