Glutathione S-transferases are a family of dimeric multi-functional enzymes involved in the cellular detoxification and excretion of endogenous substances and xenobiotics. The theta-class of GSTs is composed of two homodimeric isoenzymes designated GSTTl-I[ I] and GSTT2-2 [2]. GSTs are thought to be involved in the sensitivity of tumours to the therapeutic effects of anticancer drugs. It is therefore important to characterize the level of expression of these enzymes in both normal and neoplastic tissues. This is especially important in renal tissue since renal tumonrs are particularly refractory to chemotherapy. Cytosolic proteins f?om normal cortex and matched tumour tissues from nephrectomy patients (n=31) were resolved using a 15% SDS-PAGE system and transferred to nitrocellulose membranes using standard procedures. Theta-class GST expression was determined by directing primary antibodies against GSTTl-1[3] (monoclonal) and GSTT2-2 [4] (polyclonal) respectively. Membranes were subsequently incubated with HRP-conjugated secondary antibodies, rabbit anti-mouse Ig (GSTTI-I) and goat anti-rabbit Ig (GSTT2-2) and visualised using DAB. lmmunohistochemical localisation of theta-class GSTs was determined using the SABC-AP system.