Study participants were 191 inmates in a prison in Southern Taiwan who were suspected of having mental or psychiatric disorders. Based on case information about the offender-victim relationship, the sample was divided into incest offenders (n=39) and "other sex offenders" (n=152). After conducting descriptive statistical analyses, logistic regression was performed to distinguish any differences in psychosocial characteristics between the two groups. The incest offenders had a lower incidence of diagnosed mental disorders, fewer years of education, were more likely to be married, and were less likely to have a criminal record than other sex offenders. Incest offenders were more likely than other sex offenders to have a history of drug and alcohol abuse. Although incest offenders are less likely than other sex offenders to have mental disorders, research has shown that incest offenders who have received treatment are less likely to repeat their offenses than those who have not been treated. Since almost half of the incest offenders were married, a psychosexual analysis and treatment of the marital relationship might be a promising treatment target, along with the parent-child interaction. Treatment for alcohol and drug abuse would also contribute to improved behavioral control. 3 tables and 16 references