Genetic markers were mapped in segregating progeny from a cross between two soybean (Glycine max (L.) Merr.) cultivars: 'Minsoy' (PI 27.890) and 'Noir 1' (PI 290.136). A genetic linkage map was constructed (LOD [Symbol: see text] 3), consisting of 132 RFLP, isozyme, morphological, and biochemical markers. The map defined 1550cM of the soybean genome comprising 31 linkage groups. An additional 24 polymorphic markers remained unlinked. A family of RFLP markers, identified by a single probe (hybridizing to an interspersed repeated DNA sequence), extended the map, linking other markers and defining regions for which other markers were not available.