Since the first publication in 2004, a large number of reports have raised the question of an association between ocular adnexal lymphoma and Chlamydia psittaci. The results of this scientific debate, however, remain controversial. The primary objective of this paper was therefore to raise important questions concerning the interpretation of the different and heterogeneous data on the association between Chlamydophila psittaci and ocular adnexal lymphoma, namely the impact of the methodology used and the epidemiological variability of seroprevalence of C. psittaci antibodies. This paper also provides some methodological suggestions for future studies in the field of chlamydia-lymphoma associations.