This study was conducted to determine the prevalence and distribution of Chlamydia trachomatis genotypes in Taiwan. Urine and endocervical-swab samples were collected from two hospitals located in northern and southern Taiwan. The genotypes of a total of 145 samples positive for C. trachomatis were analysed by sequencing the omp1 gene and this was successful in 102 samples. Nine different C. trachomatis genotypes were identified. Genotype E was the most prevalent (22 %), followed by D and Da (19 %), F (16 %), J (15 %), K (11 %), G (11 %), H (6 %) and Ba (2 %). There was a geographical difference in the prevalence of genotype H (P < 0.018) between northern and southern Taiwan. Sequence mutation analysis by blast searching against GenBank reference sequences identified 12 genetic variants from a total of 102 omp1 gene sequences.