Purpose: The purpose of this study was to compare the clinical characteristics of pneumocystis pneumonia (PCP) between patients with rheumatoid arthritis (RA) being treated with biologics and those being treated without biologics. Methods: From 220 patients with RA in our institution, we enrolled 12 patients who had developed pneumocystis pneumonia throughout the course of their management. They were divided into two groups according to the treatment they were receiving for rheumatoid arthritis: the biologics group (n = 6) and the nonbiologics group (n = 6). Clinical characteristics of pneumocystis pneumonia were compared between the two groups. Results: At pneumocystis pneumonia diagnosis, the biologics group showed significantly lower serum levels of β-D-glucan and C-reactive protein than the nonbiologics group, whereas the biologics group had significantly higher lymphocyte counts than the nonbiologics group. In the nonbiologics group, lower lymphocyte counts were associated with higher β-D-glucan levels; nonetheless, this was not witnessed in the biologics group. Conclusion: The finding that rheumatoid arthritis patients being treated with biologics developed pneumocystis pneumonia with relatively normal lymphocyte counts and lower β-D-glucan levels suggests that the pathophysiology of pneumocystis pneumonia in those patients is different from that in patients being treated with other antirheumatic drugs.