AbstractThe frequency of minor chromosome variants, as detected by conventional chromosome analysis, was examined among 1,289 child psychiatric patients, of whom one‐fourth had only behavioral problems and three‐fourths had congenital abnormalities and more severe mental disorders. There was no more than random association between prominent satellites, prominent secondary constrictions or a long Y chromosome, and congenital abnormalities or more severe mental disorders. The frequencies of these chromosome variants were affected by race as has been shown in previous studies. These findings do not support the evidence for a developmental effect of minor variants in