ROSAT observed 3C 390.3 at various intervals between 18 March 91 through 30 March 91 using the PSPC instrument, providing a total exposure time of 11.5 ksec. We have constructed a background‐subtracted light curve of the source for this interval. The light curve shows no significant variability on the time scales of 200 seconds to 10 days. We also present a spectral fit to these data and discuss a search for angular structure in 3C 390.3. ©1994 American Institute of Physics