A total of 245 yeast isolates from Gunung Halimun National Park (GHNP) were screened for cellulolytic activity using 0.2% cellulose-azure. The results showed that 16 isolates have cellulolytic activity using cellulose-azure assay. These isolates were further screened for carboxymethyl cellulase (CMCase), avicelase and cellobiase using specific substrates (carboxymethyl cellulosa, avicel and cellobiose) with Teather and Wood method. The results showed that 7 isolates have CMCase; 6 isolates have cellobiase; 2 isolates have CMCase and cellobiase; and 1 isolate has CMCase and avicelase and cellobiase activities. Isolate S 4121 has the highest CMCase activity and identified as Trichosporon sporotrichoides (van Oorschot) van Oorschot and de Hoog UICC Y-286.