The objective of this study was to determine the prevalence and co-occurrence of DSM-IV personality disorders (PDs) among individuals with current DSM-IV mood and anxiety disorders in the US population and among individuals who sought treatment for such mood or anxiety disorders. Face-to-face interviews were conducted with 43,093 individuals, 18 years and older, in the National Institute on alcohol abuse and alcoholism's 2001-2002 National epidemiologic survey on alcohol and related conditions (NESARC). Odds ratios (ORs) were calculated to determine the prevalence and associations between current DSM-IV axis I and axis II disorders. Associations between mood, anxiety and PDs were all positive and statistically significant. Avoidant and dependent PDs were more strongly related to mood and anxiety disorders than other PDs. Associations between obsessive-compulsive PD and mood and anxiety disorders were significant, but much weaker. Paranoid and schizoid PDs were most strongly related to dysthymia, mania, panic disorder with agoraphobia, social phobia and generalized anxiety disorder, while histrionic and antisocial PDs were most strongly related to mania and panic disorder with agoraphobia. Results of this study highlight the need for further research on overlapping symptomatology, factors giving rise to the associations and the treatment implications of these disorders when comorbid.