The aim of this study was to define the disposition of carbamazepine (CBZ) in serum lipoproteins. The examination was conducted using the serum of 51 patients treated with carbamazepine the concentration of which was monitored 51 patients, 22 women and 29 men, 1.5-35 years old/mean 13.0 +/- 6.7 years/weighing 10.2-90.0 kg/mean 46.5 +/- 23.6/participated in the study. Every patient received carbamazepine in an individual oral dose. Concentrations of cholesterol, triglicerides, proteins and CBZ were determined. Lipoprotein fractions (VLDL, LDL, HDL and LPDS) were separated by ultracentrifugation of serum. Carbamazepine concentrations were measured by fluorescence polarization immunoassay technique on a TD x analyzer. Cholesterol, triglicerides and proteins levels were measured on Bayer--Technicon apparaturs. Carbamazepine is distributed in plasma lipoproteins, mainly in HDL fraction (mean 45.2 +/- 9.0%) and in LPDS (mean 43.2 +/- 9.3%) fraction. Ratio of carbamazepine concentration to cholesterol (RcCH), triglicerides (RcTG) and proteins concentration (RcP) and carbamazepine concentration (%) to cholesterol (R% CH), triglicerides (R% TG) and proteins concentration (%/R% P) are different in different fractions. The obtained results suggest that the disposition of CBZ in lipoprotein fractions may have a significant importance in the therapy and fat metabolism disorders make the changes of drug dose urgent.