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The Possible association of High - Mobility - Group nonhistone chromosomal pioteins with each other and with histones was studied in chromatin and in solution using bifunctional cross - linking reagent, dimethylsubrimidate (DMS). Electrophoretic analysis of cross - linked products on both acid - urea and SDS polyacrylamide gels showed a very complex pattern which was difficult to interpret. The experiment was simplified by fraction - ating the O.35M NaCl extracted proteins by ammonium sulfate, then carring out the chemical crosslinking on these groups. The results showed that HMG proteins are not self aggregating proteins like histones, but interact with other chromosomal proteins (histones). Crosslinkng of HMG proteins with histones in solution indicated that MHG1 and 2 bind to histone H1 and HMG2 interacts with dimer of H2A - H2B complex giving a high molecular weight bands (60, 000D), HMG1 7 failed to demonstrate any interaction with these proteins The results imply the possible role and binding site of HMG proteins in chromtin.