$eta$-Immunan was proteoglycan obtained from mycelium of Ganoderma lucidum IY009. In this study, the protective effects of $eta$-Immunan, against the CDDP induced in vitro cytotoxicity and in vivo renal toxicity, was measured. Concentration dependent cytotoxicities of CDDP in normal kidney cells (Vero, TCMK-l) were reduced by $eta$-Immunan treatment. Increased renal toxicity factors, such as elevation of blood urea nitrogen (BUN) and serum creatinine, reduction of kidney weight and malonidialdehyde (MDA), by intraperitoneal administration of CDDP in rats was improved. These results indicated that $eta$-Immunan have a protective effects against the CDDP induced renal toxicity, however, it needed to confirm the detailed mechanism for therapeutic effects.