A polymorphic microsatellite marker (D2S125) was recently reported to show significant linkage to non-insulin dependent diabetes mellitus (NIDDM) in a population of Mexican-American affected sib-pairs. We have used a simple non-isotopic screening technique employing the polymerase chain reaction (PCR) with a biotinylated primer to study the genetic linkage and allele frequency distribution of the D2S125 marker in a population of 109 British NIDDMs (62 possible affected sib-pairs). The analysis provided no evidence for linkage of the D2S125 marker in the British subjects (MLS = 0.029, P > 0.05). The PCR screening method used proved to be a convenient and reliable alternative to the radiolabelling of PCR products.