Abstract Observations of radio signals from an artificial earth satellite were used in a study of F-region irregularities. In general, the average height of the irregularities was found to change with magnetic latitude. Occasionally the height changes discontinuously with magnetic latitude and it is shown how this effect can be related to a thickening of the layer in the ionosphere containing the irregularities. A difference in the geographical distribution of the irregularities as observed at Boulder, Colorado and Urbana, Illinois appears to be related to a change in the latitudinal distribution of spread- F from sunspot maximum to minimum. The spectrum of irregularity size is found to consist of one or more discrete components and in general the spectra are similar for observations at two different radio frequencies.