The restriction fragment length polymorphisms of the DR-beta, DQ-alpha and -beta genes in 11 DR4 homozygous cells of different Dw type were investigated. The results showed that, with the enzyme-probe combination studied, the DR beta restriction polymorphism patterns were constant between the different cell lines. With the DQ alpha and DQ beta probes, variations in restriction patterns were obtained. No absolute correlation was seen between RFLP and Dw types. These differences may be useful in the investigation of the association between RA and specific subsets of DR4.