The effect of inclusion with beta-cyclodextrin or hydroxypropyl beta-cyclodextrin on the diffusion kinetics of Ketoprofen through a non porous lipidic membrane was analyzed starting from different dermal bases: a Carbopol gel, o/w emulsion and a fatty ointment. A constant diffusive gradient was achieved with the included forms at each concentration of the active principle in the vehicle. This suggests that the complex controls the diffusable form, according to its stability constant. The following sequence was observed for the diffusion rate: Carbopol gel greater than o/w emulsion greater than fatty ointment appears to depend mainly on the membrane/vehicle partition coefficient.