Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii is one of the most common opportunistic infections in immunosuppressed patients, particularly in patients with acquired immunodeficiency syndrome (AIDS). (1 → 3)-β-D-glucan is a component of the cell wall of P. jirovecii and other fungi such as Candida sp., Aspergillus sp. and Histoplasma sp. The measurement of serum (1 → 3)-β-D-glucan has been reported to be a highly sensitive test for PCP related to human immunodeficiency virus (HIV-PCP). We report a case of HIV-PCP not associated with elevated serum (1 → 3)-β-D glucan and highlight how HIV-PCP cannot be completely ruled out if (1 → 3)-β-D glucan is negative.