At the X chromosome workshop of the Sixth World Congress on Psychiatric Genetics, new data regarding psychiatric phenotypes and the X chromosome were presented. In the last year a number of groups have published linkage results for the X chromosome in schizophrenia, which provide no significant evidence for linkage. Presentations by groups from Cardiff, Oxford, State University of New York (SUNY), and Finland provide weak nonsignificant evidence for linkage of markers on the Xp11.4-p11.3, Xq21, and Xq26 with schizophrenia. However, the presence of a male-specific transmission ratio distorter (DMS1) that maps to Xp11.4-21.2 [Naumova et al., 1998: Am. J. Hum. Genet. 62:1493-1499] makes the interpretation of linkage findings in brotherbrother pairs difficult in this region. Regarding bipolar affective disorder, little new data were reported, but previous reports provide evidence for linkage to Xq25-q26. Summary tables of linkage results for schizophrenia and bipolar disorder can be obtained from http://www.camh.net/ research/x-chromosome/. No linkage or transmission disequilibrium of polymorphisms of MAOA and MAOB in attention deficit hyperactivity disorder was seen. Negative results for transmission disequilibrium of polymorphisms of HTR2C and MAOA with autism were provided from German and Austrian families.