The Flat Galaxy Catalog (FGC) is the result of a systematic search for disk-like edge-on galaxies with a diameter larger than a=40arcsec and major-to-minor axis ratio a/b>7 from Palomar Observatory and ESO/SERC surveys; it contained 4455 objects covering about 56% of the whole sky (Karachentsev et al., 1993AN....314...97K, see Cat. <VII/162>). The main reasons for preparing a new, improved and supplemented catalogue version were the following: - a possibility of remeasuring the coordinates of flat galaxies with a higher accuracy using the Digital Sky Survey; - the inclusion the data about "red" galaxy diameters which were absent earlier; - a reduction the diameters measured on the J and R films of the ESO/SERC to the diameter system of the POSS-I (near to a_25_ system) that eliminated the difference in photometric depth between two parts of the catalogue (Kudrya et al. 1997PAZh...23...15K); - a calculation of total apparent magnitudes (with a standard error about 0.25mag) for all flat galaxies basing on angular diameters, surface brightnesses, and other parameter data (Kudrya et al. 1997PAZh...23..730K); - a possibility to determine the Galaxy absorption values in the region of each flat galaxy placing using new IR data (Schlegel et al. 1998ApJ...500..525S). - a necessity to remove the faults noted during the work with the FGC data. The structural differences between old and new catalogue versions are: - both the parts, FGC and FGCE, have been joined in the RFGC (Revised Flat Galaxy Catalogue) where the galaxies are ranged according to their Right Ascensions for the epoch J2000.0; - the Addendum have been omitted; - the Notes describing concrete object characteristics have been included in the main corpus of the catalogue, some details were omitted; - the lists of identification of the FGC and the FGCE galaxies have been omitted because these data are accessible now due to different galaxy databases (NED, LEDA etc).