The authors investigated barriers for entering a randomized psychosocial intervention study among patients with malignant melanoma. Data on age, sex, prognostic factors, social class, marital status, mood, coping, social relations, and social desirability from participants and non-participants were compared in a regression model. More patients in lower socioeconomic classes declined participation. Non-participation was associated with low levels of distress and adaptive coping and higher levels of empathy and congruence from spouses. The type of intervention offered in this study may have more appeal to patients belonging to higher socioeconomic classes.