Three new Chlamydia trachomatis serovars were identified by several monoclonal antibodies in the microimmunofluorescence test and are proposed to be called Da, Ia, and L2a. Each was clearly distinguishable from the related serovars D, I, and L2. To date, 7, 41, and 4 isolates of the respective serovars have been identified. Each appears to be distributed worldwide. The findings meet previously established criteria for establishment of new serovars.