Pneumocystis carinii pneumonia (PCP) is a rare form of pneumonia associated with immune-suppression. It is common in patients with AIDS and with a CD4 count of less than 200 cells/mm(3). We report a case of PCP secondary to immune-suppression in a 41-year-old man with psoriatic arthritis being treated with the immune-modulatory agent etanercept. Diagnosis of PCP was made histologically using tissue obtained via transbronchial biopsy. There was a good response to standard treatment with high-dose co-trimoxazole. This report highlights a recognised but previously unreported complication of etanercept.