Primary HIV infection can occur in 40-90% of individuals recently infected with HIV. Variable symptoms usually suggestive of a flu-like illness as well as high-level HIV viraemia and steep decline in CD4 cell count are often noted. We report a case of a previously healthy homosexual man who presented with symptoms suspicious of primary HIV infection as well as non-productive cough associated with chest CT finding of diffuse ground glass appearance in lungs. Recent HIV seroconversion was confirmed. Diagnosis of Pneumocystis jirovecii pneumonia was made on transbronchial lung biopsy. The symptoms improved rapidly after initiation of treatment with trimethoprim-sulfamethoxazole. It is important to recognise that although Pneumocystis pneumonia is generally seen in the setting of AIDS, it can occasionally also occur during primary HIV infection.