INTRODUCTION: The issue of the effect of alcohol on sex related offences is complex. A comprehensive theory describing the criminal behaviours committed under the influence of alcohol has not yet been developed.

MATERIAL AND METHODS: The purpose of this paper was to evaluate and compare psychosocial and psychopathological factors characterising sexual offenders acting under or without the influence of alcohol. The study dataset consisted of 180 court ordered psychiatric-sexuological assessments issued by forensic experts from the Mental Health Outpatient Unit between 2004 and 2012 in the 10th Military Clinic Hospital in Bydgoszcz (Poland). The assessments were done for the offenders who committed sexual offences as defined in Chapter XXV of the Criminal Code in Poland: Offences Against Sexual Freedom and Morality. This study used a specially designed questionnaire: Charter for Diagnosis of Factors Determining Criminal Activity.

RESULTS: Relevant statistically significant differences have been observed between the study groups.

CONCLUSIONS: 1. The study confirmed the criminogenic effect of alcohol on sexual offences, especially rape, in both adults and adolescent population. 2. The alcohol induced disinhibition influencing the commission of sexual offence is characteristic for individuals with comorbid permanent personality disorders and organic personality disorders. 3. The offenders committing sexual offences under the influence of alcohol are found to exhibit low level of social functioning.