Human ovarian cancer cells usually have multiple specific chromosomal deletions which can be detected by cytogenetic analysis or molecular techniques. Tumour suppressor genes might be located in these deleted chromosomal segments. The importance of these different loci is usually estimated from the frequency with which they are deleted. Here we report a 59% loss of heterozygosity for chromosome 19 in the DNA of human invasive epithelial ovarian cancer from a series of 37 patients. In all cases informative on both chromosomal arms a subchromosomal loss is observed. Analysis of the same tumours for chromosome 17p and 11p loss suggests that loss of chromosome 19p/q is less important than 17p loss, but more important than 11p loss. The deletion of chromosome 19q seems to be associated with distant, hematogeneous metastasis (stage IV). In two patients with high grade tumours, the deletion involves a rearrangement of the insulin receptor locus (19p13.3). This suggests that some of the previously described frequent cytogenetic 19p+ markers and 19p13.3 breaks observed in high grade ovarian cancers, might actually occur in the insulin receptor gene.