Eight A- and F-type Ia supergiants, selected effectively at random, were all found to be variable in radial valocity. The variability is semiregular in the manner of the M-type semiregular stars. Periods derived from these eight stars and from published observations of similar stars show that they are functions of luminosity and spectral type. Several pieces of evidence suggest that the variability is due to pulsation. Values of the pulsation quantity, P(p/p0)1/2, where o is the mean solar density, are approximately constant for both early- and late-type semiregular supergiants and are equal within a factor of 2 to the value for the classical cepheids. A survey of variables in the upper part of the H-R diagram suggests that probably all stars brighter than M,, = +1 and to the right of the main sequence are variable. The values of the pulsation quantity for all these classes of variables differ from those for the classical cepheids by factors of only 2 or 3, except possibly in the case of the M giants.