The sensitivity and specificity of a newly developed ligase chain reaction (LCR) test kit were examined by the use of highly purified elementary bodies (EBs) and in situ inclusions containing reticulate bodies only. The performance of the LCR kit was compared with a commercially available polymerase chain reaction (PCR) test kit, AMPLICOR Chlamydia trachomatis. The number of EBs and inclusions of C trachomatis, respectively, at the detection limit of both kits were two EBs and one inclusion per assay. Neither kit cross-reacted with C pneumoniae, C psittaci and C pecorum EBs or reticulate bodies.