Frequency and temperature dependences of the complex permittivity epsilon* (= epsilon' - i epsilon ", epsilon' is the real and epsilon " imaginary component, respectively) were investigated for blends of polycarbonate/poly(styrene-co-acrylonitrile) (PC/SAN). In the blends, two alpha-processes corresponding to the main transitions of PC and SAN were found; for SAN at concentrations c(SAN) greater than or equal to 20 wt% and for PC for c(PC) greater than or equal to 40 wt%. The Havriliak-Negami shape parameters describing the frequency dependence of epsilon' and epsilon " are virtually independent of temperature and composition. Slight shift of temperature or frequency positions of alpha-processes found for blends from those found for neat polymers with composition of blends indicated partial miscibility of components. The concentration dependences of epsilon and epsilon " at low frequencies and high temperatures could be described with the Bottcher equation from which it followed that percolation threshold takes place for SAN inclusions at c(SAN) = 30 Wt%. Both the reduced dielectric strength Delta epsilon T and the reduced Onsager term O-t/c(SAN): (or O-t/c(PC)) in dependence on the blend composition could be qualitatively described by the Bottcher equation as well.