The distribution of serovars in 208 Chlamydia trachomatis strains of urogenital origin isolated from 185 patients attending a sexually transmitted disease clinic in Rotterdam, The Netherlands, was assessed. Typing by monoclonal antisera using a dot enzyme linked immunosorbent assay (ELISA) showed that the most common serovars were E (found in 45 strains), F (39), D (34), and K (28). Other serovars detected were H (21), G, I, I', J (two to 12), and B (one strain). Mixed infection with two serovars was detected in two patients. These results indicate that most genital infections with C trachomatis result from a small number of serovars, and that those serovars are similar in The Netherlands and Seattle, USA.