AIM: To assess the changes of portal and arterial velocities, resistance index, spleen and liver size during a long observation period (13.7 years) after orthotopic liver transplantation (OLT).METHODS: Two hundred and sixty patients were recruited retrospectively for this study and divided into groups with defined time intervals after OLT. The cross-sectional changes of portal and arterial velocities,resistance index, spleen and liver size between the defined time intervals were studied. The complications detected by ultrasound were compared to gold standard methods.RESULTS: The mean values for liver size were all within the normal range. The splenic size decreased between the time intervals 100 and 1 000 d after OLT (t;P＜0.01).While portal and arterial flow velocities decreased up to 5.5 years (t; portal velocity P＜0.01, maximal systolic velocity P=0.05, maximal end diastolic velocity P＜0.01),RI increased during this interval (t:P＜0.01). Higher RIvalues were found in older patients (r = 0.24, P＜0.001).CONCLUSION: The arterial and portal velocities show adaptation processes continuing over the course of many years after OLT and are reported for the first time. The vascular complications detected by ultrasound occur mostly up to 100 d after OLT.