The aim of this study was to compare the infectious risk between a group of psoriasis patients treated by biological drugs (BD) and a group treated by traditional systemic treatments (TST). We built a retrospective observational cohort study from the French health insurance database in the Midi-Pyrénées area (2.9 million inhabitants, southwest of France) using data from 01/01/2010 to 12/31/2013. We compared the infectious risk between 'exposed' patients treated with BD (adalimumab, etanercept, infliximab, or ustekinumab) and 'unexposed' patients treated by TST (phototherapy, acitretin, methotrexate, or cyclosporine). We realized a survival analysis on the first infectious event, defined as an anti-infective drug delivery or a hospital diagnosis of infection. We selected 101 'exposed' and 788 'unexposed' patients. In our multivariate Cox model, 'exposure' did not seem to decrease the time frame of the first infectious event compared with 'nonexposure' (HR = 0.94, P = 0.62). Among all treatment, the safest seemed to be ustekinumab while the least safe was etanercept. We found factors statistically associated with the risk of infection: gender (female vs. male), economic deprivation, chronic hepatitis B or C, history of cancer, at least one infectious event, and the number of different drugs during the 6-month period before the study. We did not find any difference of infective risk between the BD and the TST. This result enhances the recent PSONET registries conclusions.