Sulfotransferase (SULT) enzymes play an important role in the detoxification, metabolism and bioactivation of numerous xenobiotics, many dietary and environmental mutagens, drugs, neurotransmitters and hormones. The genes for SULT1A1 and SULT1A2 contain common genetic polymorphisms that are associated with individual variations in the level of enzyme activities as well as variations of biochemical and physical properties. We developed a PCR-RFLP method to analyze the frequencies of SULT1A1 and SULT1A2 alleles among cancerous patients and normal controls in Taiwan. The results showed that SULT1A1*1 and SULT1A2*1 were in positive linkage disequilibrium. Neither SULT1A1*3 nor SULT1A2*3 were found in this study. The frequencies of SULT1A1*2 and SULT1A2*2 for hepatic, colon, lung, oral, gastric, renal and cervical cancerous patients were 3.95, 5.56, 4.92, 3.84, 2.70, 7.41 and 4.50%, respectively. No statistical significance was found for these cancer patients after comparison with normal controls (4.0%) for the allelic frequencies of SULT1A1*2 and SULT1A2*2.