Synchronous rotational velocities have been calculated for 91 Algol-type systems for which the radii of the components and orbital inclinations have been published. New values of V sin i have been measured for some of these systems. The frequency of components rotating near synchronism (F less than 1.5) is found to be higher for unevolved than for evolved systems. For Algols with periods less than 10 days and radii greater than 0.2, synchronous rotation is found to be the rule. There are 50 components of spectral type B and 44 of spectral type A in systems with periods shorter than 10ḍ The shortest period in which synchronism is found is 4 days for the A-type components and 2 days for the B-type.