Rituximab has been used increasingly in the treatment of antibody-mediated rejection (AbMR) in solid organ transplantation despite the absence of clinical trials demonstrating efficacy. A contributor to the growing use of rituximab is an apparent lack of morbidity; and there are no reports of specific opportunistic infections associated with its use in renal transplant recipients. Two cases of Pneumocystis pneumonia (PCP) occurring nearly 3 years after administration of rituximab for refractory AbMR are reported herein. These cases emphasize the need for ongoing vigilant observation in patients who have received rituximab, and highlight the importance of clinical trials to establish the role of rituximab in prevention and treatment of AbMR.