Polyurethane elastomers (PUEs) based on 4,4’-diphenylmethane diisocyanate and aliphatic polycarbonate diols and/or polytetramethylene glycols have been found to be miscible with polycarbonate (PC). Incorporation of 0-10% of PUEs in melt mixing decreases the glass transition temperature of PC (by 0-30 degrees C), facilitates its processing, and improves its resistance to hydrothermal ageing. No phase separation in blends was detected by means of the absorption of the visible light and differential scanning calorimetry measurements. Dynamic mechanical and static bending measurements concurrently show a slight increase in the glassy state modulus, which can be viewed as an ’antiplasticizing’ effect of PUEs in PC. This effect and the miscibility of PC with PUEs can be ascribed to their strong interaction, probably due to the formation of hydrogen bonds between urethane and carbonate groups.