The relationship between the inversion channel mobility of 4H-SiC Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) and crystalline qualities of epitaxial layer has been investigated. The channel mobility of 14.6 cm(2)/Vs was obtained from the 4H-SiC MOSFETs fabricated on the epitaxial layer with the doping concentration of 1.8 x 10(15)cm(-3) when the gate oxidation was performed by dry thermal process. It was found that the channel mobility has a correlation with doping concentration, surface roughness and crystalline qualities examined by full width at half maximum (FWHM) of x-ray rocking curve and photoluminescence intensity of near band gap emission.