This report constitutes the seventh update of the human obesity gene map incorporating published results up to the end of October 2000. Evidence from the rodent and human obesity cases caused by single-gene mutations, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci uncovered in human genome-wide scans and in cross-breeding experiments in various animal models, and association and linkage studies with candidate genes and other markers are reviewed. Forty-seven human cases of obesity caused by single-gene mutations in six different genes have been reported in the literature to date. Twenty-four Mendelian disorders exhibiting obesity as one of their clinical manifestations have now been mapped. The number of different quantitative trait loci reported from animal models currently reaches 115. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 130 studies reporting positive associations with 48 candidate genes. Finally, 59 loci have been linked to obesity indicators in genomic scans and other linkage study designs. The obesity gene map reveals that putative loci affecting obesity-related phenotypes can be found on all chromosomes except chromosome Y. A total of 54 new loci have been added to the map in the past 12 months and the number of genes, markers, and chromosomal regions that have been associated or linked with human obesity phenotypes is now above 250. Likewise, the number of negative studies, which are only partially reviewed here, is also on the rise.