Several limitations of this study should be noted. First, our restrictive criteria for continuous abstinence may have meant that the sample size of successful quitters was smaller than in previous studies. Another aspect to consider is the test used for the assessment of personality. In spite of the long tradition of using the NEO PI-R in general population, measures for clinical population are missing. Among the strengths of the present study, we should note that a 12-month follow-up was carried out, continuous abstinence was biologically confirmed, and facets of personality instead of factors were analyzed, thus making possible, from a clinical perspective, the design of more specific interventions for smoking cessation.