The cytokine interleukin-1 (IL-1) plays a key role in the pathogenesis of inflammatory and immune diseases. Several disease-genotype association studies have addressed the question whether genetic determinants of outcome or severity of disease exist. These studies were hampered by the lack of highly polymorphic markers in the interleukin-1 beta (IL-1B) and IL-1 receptor antagonist (IL-1RN) genes. Polymorphisms in these two genes were searched for in order to increase informativity. Here a novel BsoF I dimorphism and the characterization and PCR detection of a previously identified Taq I polymorphism in the IL-1B gene is reported. Furthermore, in the IL-1RN gene four novel diallelic markers were identified. Little linkage disequilibrium is observed between the two markers in IL-1B gene. Similarly, some of the markers in IL-1RN gene show little linkage disequilibrium. Using the markers described here it is possible to reach a better level of informativity in genotype-disease association studies.