Pneumocystis is an atypical fungus causing pneumonia in immuno-compromised individuals. Though previously termed as Pneumocystis carinii, the recent taxonomy has considered human derived Pneumocystis to be a different species Pneumocystis jiroveci. The organism is the most common cause of opportunistic infections among patients with acquired immunodeficiency syndrome (AIDS) in developed countries. Incidence of Pneumocystis pneumonia or pneumocystosis in developing countries including India continues to be low. Microscopy of appropriate clinical samples has been the mainstay of diagnosis of pneumocystosis. Amplification techniques are now being evaluated for detection of P. jiroveci. This review attempts to give a recent update on P. jiroveci with special focus on epidemiology, taxonomy, current diagnostic modalities and recommended immuno-prophylaxis.