Tabatabaian F, et al. - This research was formulated in order to investigate the effect of thickness of monolithic zirconia ceramic on its final color and to define the minimum thickness required for gaining an acceptable final color. It was reported that the thickness of monolithic zirconia ceramic exerted an impact on its final color. To gain the acceptable final color, data recommended that the minimum thickness of a monolithic zirconia ceramic ought to be 0.9 mm.