Monitoring of fibrosis process with the use of histopathologic studies on liver's bioptates is limited, so it is attempted to find reliable, obtained with less invasive methods, sensitive and reflecting fibrosis dynamics markers of this process. The aim of the study was simultaneously to assess liver's expression as well as circadian and mean daily TGF-betal concentration in serum of patients with chronic hepatitis type B in comparison to control group. Studies were performed on 50 patients (9 women, 41 men) aged 45.9 +/- 2.3 years with chronic hepatitis type B. Control group consisted of 20 patients (mean age 38.6 +/- 3.7 years), in which so called minimal changes without fibrosis were observed in histophatologic bioptate of liver. Blood for studies was collected every 4 houres during the day. Serum concentration of TGF-betal was assessed with the use of ELISA method, and expression of mRNA TGF-betal in liver with QRT-PCR method. No significant difference between circadian as well as mean daily serum TGF-betal concentration beetwen control group and the group with chronic hepatitis type B was shown. Increased expression of mRNA, TGF-betal in bioptate of liver of patients with chronic hepatitis type B in comparison to control group was noted. In "minimal changes" control group presence of significant positive correlation between expression of mRNA TGF-beta1 in liver and concentration of this cytokine in serum was shown, in the group of patients with chronic hepatitis B this connection was not noted.