We report Pneumocystis carinii pneumonia (PCP) diagnosed by bronchoalveolar lavage cytology and transbronchial lung biopsy in three out of five human immunodeficiency virus (HIV) positive adult patients presenting with interstitial pneumonitis. One of these patients was serologically positive for HIV at the time of presentation and the remaining two patients were detected to be HIV positive on follow up after the diagnosis had been established. All the three patients were treated with co-trimoxazole. One patient recovered and was discharged; another patient improved with treatment but died after jugular vein cannulation and the third patient succumbed to cryptosporidial diarrhoea. The remaining two patients with non-specific interstitial pneumonitis treated with prednisolone and bronchodilators were recovered and were discharged from the hospital.