Chlamydia trachomatis is one of the important pathogens of STD in our country. Therefore, rapid accurate, reliable and convenient tests for its detection are required. So far, IDEIA Chlamydia has been employed as a useful diagnostic kit. Now, IDEIA PCE Chlamydia, applied as a dual amplification EIA method, has been developed. In our present studies, the sensitivity, reproducibility, cross reactivity, and reliability of IDEIA PCE Chlamydia were investigated and compared with those of IDEIA Chlamydia and LCR Chlamydia. The sensitivity of IDEIA PCE Chlamydia showed 2.4 x 10(2) IFU/ml for C. trachomatis D, 1.2 x 10(2) IFU/ml for C. trachomatis E, 3.8 x 10 IFU/ml for C. trachomatis F, and 1.25 x 10(2) IFU/ml for C. trachomatis L2. With regard to reproducibility, more than 2.4 x 10(2) IFU/ml of all strains of C. trachomatis and negative samples gave highly reproducible values. Though no cross reactivity was recognized among three strains of Staphylococcus aureus with concentrations of more than 10(9) IFU/ml, non-heated samples of over 10(6) CFU/ml showed cross reactivity. In our observations, phosphate, Mg2+, Ca2+, and Fe3+ inhibited the efficacy of both IDEIA and IDEIA PCE Chlamydia. Ca2+ per se could be an inhibitor in the case of urine samples analyzed by IDEIA and IDEIA PCE Chlamydia. These results indicate that IDEIA PCE Chlamydia kit for detection of C. trachomatis may be clinically useful because of its improved sensitivity over IDEIA Chlamydia and its invariable specificity and reliability.