The combined effect of film thickness and grain size diameter on the temperature coefficient of resistance of a uniform continuous polycrystalline metal film of thickness greater than the intrinsic mean free path has been theoretically investigated. It has been found that the value of the temperature coefficient of resistance decreases with decrease in grain size. For very small grain size it is less than the bulk value and may be negative in some cases, whereas for very large grain size and film thickness it approaches the bulk value.