The aims of this study were to evaluate the prevalence of HCV-RNA in different fractions of saliva taken from patients with chronic hepatitis C, to establish whether virologic parameters or disease severity exert any influence on the detectability of HCV-RNA in saliva, and to evaluate the prevalence of HCV infection in partners of HCV-infected subjects with respect to the presence of HCV-RNA in saliva. Sera samples and different fractions of saliva (whole saliva, surnatant, and cell fraction) from 48 subjects (45 with chronic hepatitis C and three healthy anti-HCV+ carriers) were examined for HCV-RNA by RT nested PCR and DEIA hybridization. HCV-RNA-positive sera were also tested for genotype and viral titer (bDNA2 method). Twenty-seven stable sexual partners (25 females and 2 males) were screened for anti-HCV antibodies at least twice over a minimum of 12 months. HCV-RNA was detected in the sera of 39/45 patients and of 22/39 viremic patients. In all of the latter, the presence of HCV-RNA was restricted to the cell fraction. Viral titer was significantly higher in patients with HCV-RNA in saliva than in those without (12.3 x 10(6) versus 4.6 x 10(6) eq/ml, P < 0.01). HCV-RNA positivity was unrelated to genotype, duration of disease, Hepatitis Activity Index scores or transaminase levels. Anti-HCV was positive in one of 13 sexual partners of patients with HCV-RNA in saliva and in 1/14 of those without (P = NS). In conclusion, HCV-RNA is detectable in the cell fraction of saliva in a high proportion of highly viremic patients with chronic hepatitis C, but its presence does not seem to be associated with an increased risk of HCV transmission among sexual partners.