We investigated the frequency of Hepatitis C Virus antibodies (anti - HCV), using 2nd generation Enzyme Linked Immunosorbent Assay (ELISA - Abbott Laboratories), in 83 cancer patients (54 males, 29 females) with a mean age of 48.2 years (range 17 - 82). Of the 83 patients, 11 (13.2 %) were positive for anti - HCV and this frequency was higher than the prevalence of 0.0 % - 0.6 % reported for the normal Turkish population. The history of blood transfusion (72.7 % vs 37.5 %), operation (45.4 % vs 30.5 %) and hepatitis (9.0 % vs 8.3 %) were more frequent in the group with HCV antibody compared to the group without HCV antibody, but the differences were not statistically significant (p> 0.05). The frequency of elevated alanine aminotransferase (1.5 times upper limit of normal) was higher in anti - HCV positive patients compared to patients without anti - HCV antibody (p=0.0015). Our results indicate that cancer patients are vulnerable to HCV infection.