This report summarizes the findings presented at the Chromosome 4 Workshop of the Sixth World Congress on Psychiatric Genetics (October 1998, Bonn, Germany). Chromosome 4 linkage and association results for several psychiatric phenotypes including bipolar affective disorder, schizophrenia, alcoholism, and mental retardation are reviewed. In bipolar affective disorder, positive linkage results for markers on 4q35 were reported by three independent groups. In addition, findings in bipolar disorder were reported for markers spanning 4p14-16, and of particular interest are the results that coincide with the original Blackwood et al. [1996: Nat Genet 12:427-430] region at 4p16. For schizophrenia, modest positive results were reported for 4q31, as well as for marker D4S2917 at a region of 4q close to the centromere. Chromosome 4 continues to demonstrate interesting results in alcoholism, particularly in the region of the alcohol dehydrogenase gene cluster; however, it is not clear how to interpret the contrast in the susceptibility versus protective loci that are being reported in this region.