During the 20 year interval from 1958 to 1978 a change in the spectrum of disease, etiology, and diagnosis of mucormycosis was observed at The Mount Sinai Hospital. Although the rhinocerebral and pulmonary forms of mucormycosis were still the most frequent forms of disease, hospital acquired cutaneous and subcutaneous infections emerged. Since 1974, 14 of 15 cases of mucormycosis were diagnosed during life. Rizopus species, especially R. rhizopodoformis, have been the etiologic agents identified in 13 of 14 culturally proven cases. The presence or absence of antirhizopus fungistatic activity and antirhizopus antibody in the sera of six of the patients was correlated with the severity of clinical disease. Preliminary results showed a relationship between the extent of disease and the degree of serum fungistatic activity that was independent of antibody production.