We studied the relationship between personality profiles, breathlessness perception and clinical and functional features in 36 outpatient asthmatics (12 females; age range: 18-52 yr). Each patient underwent psychometric evaluation with Minnesota Multiphasic Personality Inventory (MMPI). Breathlessness perception was evaluated by Borg's scale during methacholine (M) challenge, and PS20 (the perception score obtained when FEV1 fell by 20%) was recorded. Baseline FEV1 values ranged from 70.0 to 126%. PC20 M values ranged from 0.05 to 31.7 mg/ml. According to a symptoms score system (0 to 12 points), 12 asthmatics were classified as mild, 12 as moderate, and 12 as moderate/severe. We did not find any specific personality profile in asthmatic patients. Sixteen asthmatics had at least one MMPI subscale score indicative of psychological disturbances. We found a significant trend from mild to moderate and moderate/severe asthmatics (p < 0.015), when the number of asthmatics with subscale scores indicative of psychological disturbances was compared to that of asthmatics with normal scores. Moreover, we found that the asthmatics with scores indicative of hypochondriasis showed a significant trend from mild to moderate and moderate/severe asthma (p < 0.015). Furthermore, in all asthmatic patients, hypochondriasis scores were positively correlated to asthma severity score (p < 0.02). PS20 values ranged from 0.1 to 8.1. Twelve asthmatics were hypoperceivers (PS20 < or = 1) and four were hyperperceivers (PS20 > or = 5). We observed a significant trend from mild to moderate and moderate/severe asthmatics (p < 0.025) when we compared the number of hypoperceivers to that of normoperceivers. In conclusion, we found that in outpatients with different grading of asthma, severity of disease is linked to psychological disturbances and poor perception of breathlessness, additionally, hypochondriasis was related to disease severity in all patients.