The influence of anticellular antibodies on reading and interpretation of Chlamydia-specific antibodies was investigated with selected sera in three commercial tests before and after absorption with noninfected cells. In two tests using C.trachomatis-L2-infected BGM- and L 929 cells, respectively, several sera could not be evaluated by unspecific reactions. The test system using only elementary bodies of C.trachomatis L2 showed no unspecific reactions.