Abstract: The coefficients of thermal expansion of unidirectional fiber reinforced composites are investigated by use of homogenization method. The relationship between coefficients of thermal expansion and component properties and volume fractions is determined. A conclusion is obtamed that the influence of the property ratios of fiber and matrix on the transverse coefficients of thermal expansion is more important than on the longitudinal ones. The predictions from homog-enization method and four other analytical methods are compared with each other,and with experimental data. The assessment of validity of these different methods is made and the reliability of homogenization method is verified.