Histoplasmosis is a common infection endemic in many regions of America, Asia, India and Africa, with sporadic cases also occurring throughout the world. Although excellent laboratory methods for diagnosis are available, there are deficiencies that must be met by continued research. Clinicians and laboratory directors must be familiar with the uses and limitations of a battery of serologic and mycological tests to accurately diagnose histoplasmosis. Research is needed to reduce false-negative and false-positive results, and to improve the identification of the organism in tissues. Approaches to the diagnosis of histoplasmosis and areas that require further research will be reviewed.