Purpose The time course of changes of the liver function after stereotactic body radiotherapy (SBRT) was analyzed in patients treated for non-resectable hepatocellular carcinoma (HCC). Patients and methods Twenty-six patients with non-resectable HCC treated with SBRT were included in this study. Clinical, biochemical and treatment-related parameters were retrospectively collected. S-albumin, s-bilirubin, s-alkaline phosphatase (AP) and s-alanine transaminase (ALAT) at 0, 3, 6, and 12 months after radiotherapy were analyzed. Results Seventeen and nine patients were Child-Pugh class A and B, respectively. The liver was exposed to relatively high radiation doses with mean doses of 1.9-26 Gy. None of the patients developed classic radiotherapy-induced liver disease (RILD), but two patients developed non-classic RILD. Two patients developed grade 3 ascites and no grade 4-5 toxicities were observed. Six patients declined in Child-Pugh class. The s-albumin decreased significantly from a pretreatment median of 37.4-34.36 g/l at three months after SBRT and stabilized thereafter. S-bilirubin, s-AP and s-ALAT did not change significantly over the study period. Conclusion Despite the fact that patients received high radiation dose to the liver, there was only moderate morbidity related to the treatment. The s-albumin decreases over three months after SBRT reflecting minor to moderate hepatic toxicity. S-albumin should be observed in the follow-up of HCC patients treated with SBRT.