The Inventory of Interpersonal Problems (IIP) is a self-report instrument, designed to measure interpersonal distress. The properties of the Swedish IIP-version were studied in three different samples: non-psychiatric subjects, psychiatric out-patients, and psychiatric in-patients. The Swedish data were compared with Horowitz' normative American IIP-data. The patterns of correlation between the Swedish IIP and personality characteristics as assessed by personality inventory, self-report measures of alexithymia, and interview-based psychodynamic interviews were investigated. The results indicate that the Swedish IIP version possesses acceptable internal consistency, and construct validity in terms of its circumplex properties, and that it manifests meaningful patterns of correspondence with the self-report and interview-based instruments, developed within other theoretical frameworks, for assessing personality characteristics. For example, the pattern of correlations between the IIP and the alexithymia measures suggests alexithymia to be associated with problems of intimacy avoidance.