The median angular sizes in different redshift bins were plotted as a function of (1+z) for bright steep spectrum radio galaxies and quasars, both together and separately. These were compared to the theoretical curves for an Euclidean universe, and for a Friedmann universe with linear size evolution of the forml∼(1+z)-x withx=3. It was found that for the sources as a whole, the variation of angular diameter with redshift behaved as expected in an Euclidean universe, which can also correspond to a Friedmann universe with linear size evolution and 1<x<z. There was a trend for the sources at low redshift (z≲0.6) to exhibit steeper linear size evolution withx∼3. However, if this trend should continue to higher redshifts, this would imply that the linear sizes of radio galaxies and quasars evolve differently with quasars evolving less strongly than radio galaxies.