The suggestion by D'Angelo (1976) that E region field-aligned ionospheric irregularities might be detectable by an auroral zone riometer is examined. Results of a study of rapid (≲60-s period) variations of the Siple Station, Antarctica (L≂4.2), 30-Mhz riometer signal are that the occurrence statistics of these variations are under control of universal time rather than sidereal time; there is a night-day asymmetry and a quiet time afternoon secondary maximum in occurrence rate, and there is no significant difference in the occurrence rates of small variations initially deflecting above or below the background level of quasi-steady signal. These conclusions are not in conflict with absorption, but cannot be explained by scattering from field-aligned irregularities. A maximum of ≂30% of all rapid variations can be accounted for by the scattering interpretation, and the study results are consistent with a zero rate (null hypothesis). Calculations of the expected amplitude of variations due to scattering are derived by three different methods. All predict amplitudes lower than the 0.25- to 1.0-dB range reported by Mehta and D'Angelo (1980), but not too low to render them undetectable by a sufficiently sensitive riometer.