To contribute to the understanding of the influence of gender bias on the diagnosis of DSM-IV-TR personality disorders, several research topics were discussed: sex differences in prevalence, the role of biopsychosocial influences on the concept of personality disorders, and the diverse sources of gender bias. In the present study, the influence of sex is investigated in a large stratified sample of the Flemisch population (n=957), in which DSM-IV-TR Axis-II diagnoses were obtained using the Assessment of DSM-IV Personality Disorders (ADP-IV; Schotte & De Doncker, 1994). Initially, sex influences were analysed on the dimensional Trait-scales with t-tests. Next, differential sex prevalaneces were compared using contingency analyses. In search of possible gender bias, Differential Item Functioning (DIF) analyses were conducted at dimensional Trait-level and categorical criterion level. the findings concerning the DIF analyses may indicate that some criteria tend top manifest differently in men and women. The results have implications for clinical practise and research regarding sex differences in personality disorder prevalence rates.