Linkage analysis was used to determine map positions for 18 short tandem repeat polymorphisms that continuously span 186 cM of human chromosome 3. Mapping was based on the genotyping of 40 CEPH reference families. Loci order from pter-qter was D3S1252-D3S1235-D3S1234-D3S1233- D3S1254-D3S1251-D3S1215-RHO-ACPP- D3S1238-D3S1206-D3S196-D3S1237- (D3S1253,D3S1439)-D3S1243-D3S1232-SST. Odds against inversion of adjacent markers in all cases were 700:1 or better, except for the marker pair at D3S1253,D3S1439 that was not separated by any recombinants and therefore could not be ordered. Only one gap greater than 25 cM on the sex-equal map was observed.