To detect hepatocellular carcinoma (HCC) cells in the circulating peripheral blood, we previously designed a highly sensitive reverse-transcription polymerase chain reaction (RT-PCR) method targeting alpha-fetoprotein (AFP) messenger RNA (mRNA). Using this method, we analyzed peripheral blood of in- and out-patients bearing HCC for 2 months consecutively and examined the outcome thereafter. All 11 patients with recurrence either in the liver alone or in both the liver and the lung were positive for AFP mRNA. Among 10 recurrence-free patients, 2 patients were AFP mRNA-negative and remained recurrence-free during a period of 22 months observed. Four of 8 AFP mRNA-positive, recurrence-free patients developed a clinically evident recurrence in the liver after 2 to 16 months. Seven of 8 preoperative patients were already positive for AFP mRNA and the remaining negative patient became positive during surgery. Four of 6 preoperatively positive and still-alive patients had recurrence in the liver after 2 to 9 months. None of the HCC-negative patients were positive for AFP mRNA. We actually found an AFP protein-positive cell in peripheral blood obtained from one of the AFP mRNA-positive patients by immunostaining. The present results suggest that circulating HCC cells may have some relationship with the recurrence of HCC in the liver.