The effect of cyclotron irradiation by 38‐Mev alpha particles on the steady‐state creep rate (ca10−6per second) of aluminum has been measured at beam densities up to 1.2×1013particles per cm2per second. The data, which were taken on a 0.016‐inch thick aluminum specimen for a stress range of 600 to 2500 psi and over a temperature range of 160° to 330°C, showed a slight decrease in rate (up to 19 percent) during irradiation. Since the effect is small, apparently independent of beam density, and is comparable to the usual deviations in the absence of radiation, it can be considered a null result.