Aim. The aim of the present study was to compare positive and negative urgency as well as sleep quality among patients with borderline personality disorder (BPD) and antisocial personality disorder (ASPD). Sample and method. This was a causal-comparative study. The sample included 50 patients diagnosed with ASPD and 50 patients diagnosed with BPD, as well as 50 healthy controls. All subjects were selected based on availability. The instruments used were Lynam et al.'s Impulse Control Scale and Pittsburgh's Sleep Quality Index. Results. The results show that the mean of negative urgency is significantly higher in BPD patients than in ASPD patients, whereas the mean of positive urgency is significantly higher in ASPD patients than in BPD patients. Dimensions of sleep quality in both BPD and ASPD patients are significantly higher than for healthy controls (p<0.01). Discussion. a significant difference exists among the BPD and ASPD patients and healthy controls in the positive and negative urgency and sleep quality. Conclusion. We found that BPD and ASPD patients manifest reckless behaviours both due to more negative urgency when experiencing negative emotional situations and due to positive urgency when experiencing positive emotional situations. Both patient groups show lower sleep quality, which has diagnostic and therapeutic implications.