We have improved the protocol of In-Gel Competitive Reassociation (IGCR) technique, one of genome subtraction methods, and developed the apparatus for this technique. The protocol obtained by the fluorescence monitor that we had reported on this symposium last year was added to the improved IGCR technique, which made IGCR method simple and less time consuming for handling. The comprehensive subtractions with genes from twins, one of whom with rheumatoid arthritis, were employed and IGCR libraries were constructed. The analysis of the library clones will be reported.