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Previous studies linked infection by Chlamydia psittaci to ocular adnexal lymphomas in Italian patients (Ferreri et al., JNCI 2004). Patients treated with doxycycline to eradicate the organism have demonstrated disease regression (Ferreri et al., J. Clin Oncol, 2005). To assess whether Chlamydia psittaci is associated with ocular adnexal lymphomas in a North American population, we studied 24 ocular adnexal lymphoma biopsy specimens from adults, 16 control lymphoma specimens from patients with systemic lymphomas not involving the ocular adnexa and five benign control ocular tissue samples. There were fifteen MALT, five diffuse, large B-cell, three follicular, and one mantle cell lymphoma specimens. The presence of Chlamydia psittaci DNA was investigated by PCR in each group. DNA was isolated from sections of formalin-fixed, paraffin-embedded tissue. Two different assays were utilized: 1) a previously published conventional PCR/gel based assay targeting a 111 bp fragment of the 16S gene [Madico, J. Clin Micro, 2000] and 2) a realtime PCR assay amplifying a 148 bp portion of the 16S gene with detection via a specific fluorescent probe. Amplification was carried out to 60 cycles. Positive controls consisted of isolated DNA from Chlamydia psittaci strain VS1, CP3, and FP. A human DNA internal control was utilized to assess DNA quality and amplification success. Both assays detected Chlamydia psittaci DNA from isolated strains. All patient samples in all categories yielded negative results using both assays. Thus, we could not confirm that Chlamydia psittaci is associated with ocular adnexal lymphomas in our patient population. Differences in the prevalence of Chlamydia psittaci infection in North America and Europe or technical differences in application of the assays may underlie the differences in our findings when compared to the Italian series. Confirmation with larger numbers of specimens is required.