An imbalance of the immune system and mixed personality profiles in suicide attempters have been reported. As suicidal behavior is common in patients with psychiatric disorders within the spectrum of depressive features, in this study we measured soluble interleukin-2 receptor concentrations in plasma (sIL-2R) and investigated temperament and character profile and their potential correlation in formerly depressed patients with a history of suicide attempt. We studied sIL-2R levels in plasma and personality characteristics (using Cloninger's Temperament and Character Inventory [TCI]) of formerly depressed patients who had attempted suicide a mean of 3 years previously (n = 25), and age and gender matched normal controls (n = 25). There was no significant difference in sIL-2R levels between formerly depressed suicide attempters and age and gender matched normal controls (0.23 ng/ml plus or minus 0.25 vs. 0.19 ng/ml plus or minus 0.16). When compared to normal controls, suicide attempt patients had a significantly higher score on the temperament dimension "harm avoidance" and a lower score on the character dimension "self-directedness." No significant correlation was found between sIL-2R values and TCI dimensions. We propose that the liability to suicidal behavior among suicide attempters susceptible to depressive symptomatology may be related to high harm avoidance and low self-directedness.