Treacher Collins syndrome (TCOF1) is an autosomal dominant disorder of craniofacial development in which there is considerable variability in the clinical manifestations. The TCOF1 locus has previously been mapped to chromosome 5q32-33.2 and markers flanking the disease locus identified. In the current investigation we have analysed eight short tandem repeat polymorphisms for linkage to TCOF1 in a large family with multiple affected individuals. Linkage analysis suggested that TCOF1 in this family was linked to markers in the region 5q32-33.2. We have used the results to make diagnostic predictions in certain mildly affected and apparently unaffected individuals.