ROSAT all sky survey observations of IRAS galaxies.

A sample of 14708 extragalactic IRAS sources selected from the Point Source Catalog via statistical classification has been cross- correlated with the ROSAT All Sky Survey. We present the resulting catalogue of 244 IRAS galaxies positionally coincident with ROSAT X-ray sources. For 222 of them optical counterparts could be identified by comparison with the NASA/IPAC Extragalactic Database. The sample of X-ray emitting IRAS galaxies comprises infrared luminous nearby galaxies, spirals and ellipticals, Seyfert galaxies, and QSOs. It is dominated by galaxies with active nuclei, unlike the sample of IRAS galaxies which have not been detected at X-ray wavelengths, at least in part due to the flux limitations of the ROSAT survey. An unexpected result is the discovery of several spiral galaxies with luminosities up to 10^43^erg s^-1^ well above those found with the Einstein satellite. This suggests as possible explanation that the X-ray luminous spirals are starbursts which are characterised by steep spectra and thus are more easily detected by ROSAT. The X-ray properties are studied as function of IR and optical fluxes for the different subgroups of galaxies in the sample. In general, we found a positive correlation between the X-ray luminosity and the IR and optical luminosities, respectively, which is steepest for Seyfert galaxies. The latter also appear to be separated from the other classes in correlations involving X-ray to IR or optical flux ratios. The X-ray to IR or optical flux ratios will be valuable for preselecting Seyfert galaxies when comparing X-ray to IR or optical surveys. Finally, by taking Seyfert galaxies into account we remove the trend of an increasing ratio f_x_/f_opt_ with decreasing optical absolute magnitude which had been found for X-ray bright QSOs alone.