Since /9-1,3-glucan is a common component of fungal cell wall, its detection might be useful in diagnosing invasive candidiasis. Not only endotoxin but /3-1,3-glucan activates proclotting enzyme contained in a conventional chromogenic limulus test (CCLT). Endotoxin activates this enzyme through factor C, while the /3-1,3-glucan activates through factor G. Since endotoxin specific test (EST) contains factor C, endotoxin would be quantified. By subtracting EST value from CCLT value, β-1,3-glucan would be quantified. We named this value Fungal Index (FI), and examined if it actually reflects the candidal infection. Ninety-two patients were tested for CCLT and EST prospectively. FI increased significantly in candidal infection (p<0.05) but remained low in GNR infection. Moreover, FI increased proportionally to the severity of candidal infection. Elevated FI decreased when antifungal therapy was successful. Thus FI was a useful index not only in the diagnosis of invasive candidiasis but also in the evaluation of antifungal therapy.