Blood alpha-fetoprotein messenger RNA (AFP mRNA) is thought to be a marker of hepatocellular carcinoma (HCC). Its value as a predictor of HCC in patients at risk is not known. A series of 201 patients with compensated cirrhosis (114 men, mean age 58 years) underwent surveillance with semi-annual ultrasound and serum alpha-fetoprotein measurements. Total RNA was extracted from peripheral blood mononuclear cells collected at different intervals and AFP mRNA was retrotranscribed and amplified by nested polymerase chain reaction. Ten patients with HCC and 30 blood donors were used as controls. Three patients with HCC, 39 with cirrhosis under surveillance and four blood donors circulated AFP mRNA (30, 20 and 13%, NS). During 50 months of surveillance, 27 patients with cirrhosis developed HCC: the tumour was detected more often in patients with higher than normal baseline serum AFP (> or =7 IU/L) than in those with normal AFP levels (21%vs 9%, P = 0.02). The incidence of HCC was the same in patients with and without AFP mRNA at baseline (15%vs 14%). In 53 patients, AFP mRNA was re-tested after 6-25 months of surveillance. HCC developed in two of 11 (18%) who were initially AFP mRNA positive and later became negative, in none of those who were initially negative and later became positive and in two of 39 (5%) who remained persistently negative. In conclusion, blood AFP mRNA is not a sensitive predictor of HCC in patients with compensated cirrhosis.