Abstract A therapeutic transdermal system based on ethyl cellulose polymer and matrix diffusion-controlled release of an antimalarial, primaquine (PQ), was investigated with respect to the in vitro percutaneous penetration and in vivo skin absorption profile of the drug. In order to correlate in vitro and in vivo data, pharmacokinetic modelling was performed. Thus, the diffusion of the drug through the polymeric device and its pharmacokinetics parameters were both considered. Franz-type diffusion cells were used for in vitro determinations. In vivo experiments were performed with Swiss mice. Drug plasma profiles following transdermal treatment showed constant primaquine plasma levels, indicating controlled and systemic delivery of the drug over a period of 40 h.