There is extensive evidence that there is a genetic component to developing primary open-angle glaucoma (POAG). Unraveling this genetic component might clarify the pathophysiology of the disease and greatly assist in treatment and prevention of visual loss of many thousands of individuals. Linkage and association studies have helped identify loci and genes involved. The vast majority of the known heritable component of POAG, however, remains to be elucidated. Future studies should further investigate the identified loci and their role across different populations; assess genetic interactions and genotype-phenotype correlations; and aim at identifying new POAG genes by modern sequencing techniques.