In a single-blind pharmacokinetic study patients being treated with conventional carbamazepine (CBZ) in a t.i.d. regimen were randomly allocated to identical doses of two CBZ slow-release formulations (Trimonil Retard and Tegretol Retard) administered once daily. Statistical analysis involved the following parameters: AUC, Cmin, Cmax and Fluctuation Index (FI). With regard to Cmin and FI statistically significant differences in favour of Tegretol Retard were observed.