“…Erythromycin has been most commonly used for ocular and genital chlamydial infections, especially of newborns and pregnant women, but is has several disad vantages including instability in gastric acid, gastrointes tinal disturbances, and a short terminal half-life in serum [7], Recently, new derivatives of MLs with more favor able pharmacokinetic characteristics than erythromycin have been developed: roxithromycin [8], clarithromycin [9], and azithromycin [10,11], The MIC values of MLs are a little higher than those of TCs, but clarithromycin has an excellent activity against Chlamydia which is com parable with TCs (table 1).…”