Abstract: An aroma diffuser assembly for dispensing an aroma from a replaceable and expendable cartridge is provided. The cartridge includes a porous block for holding a relatively large quantity of aroma producing liquid and a protective cartridge housing for covering the block to allow handling of the cartridge without coming in contact with the block. The assembly includes a diffusion housing containing a heater assembly and blades for coupling the heater assembly to an electrical outlet. The diffuser housing is adapted to receive the cartridge and support it above the heater assembly. The cartridge housing and block have slots and channels aligned with a slot in the diffusion housing to allow heated air to impinge on the block to vaporize the liquid and to pass freely into the ambient atmosphere. Should condensation of the vapor occur on the interior walls of the cartridge, the condensed liquid is collected by troughs at the bottom of the cartridge.