Sera from 164 Saudi Arabian patients with non-A, non-B hepatitis liver disease were examined for antibodies to hepatitis C virus (HCV) by second- and third-generation recombinant immunoblot assay (RIBA-2 and RIBA-3) and for HCV RNA by polymerase chain reaction (PCR). By using RIBA-2, 92 (56.1%) were reactive, 64 (39%) were nonreactive, and 8 (4.9%) were indeterminate. By using RIBA-3, 98 (59.7%) were reactive 60 (36.6%) were nonreactive, and 6 (3.7%) were indeterminate. By using PCR, 108 (65.9%) were positive. Of the eight RIBA-2 indeterminate samples, seven became RIBA-3 reactive but PCR-positive, and one became RIBA-3 nonreactive but PCR-negative. Of the six RIBA-3 indeterminate samples, five were RIBA-2 nonreactive but PCR-positive, and one was RIBA-2 reactive but PCR-negative. From our study on Saudi patients, we conclude that RIBA-3 has slightly but not significantly improved the results of anti-HCV antibody detection, and is probably of more value to resolve those indeterminate samples by RIBA-2. Although expensive, PCR remains the most reliable HCV diagnostic method until an HCV antigen detection test is available.