The lack of control procedures inherent in most of the experiments conducted to assess the effectiveness of skin temperature biofeedback in the treatment of Raynaud's disease renders the results inconclusive. In this study, control groups and a double-blind approach are adopted. Thirty-six patients, carefully screened for a diagnosis of primary Raynaud's disease, were assigned to a skin temperature increase group (N=12), to an EMG relaxation control group (N=12), or to a notreatment control group (N=12). All patients kept records of their symptoms for the duration of the study. Each subject in the two training groups received 20 sessions, the last 2 conducted under cold stress. Data analysis according to original group assignment, as well as following regrouping of subjects according to several learning criteria, showed that while all patients reported a marked decrease in the number of vasospastic attacks, no significant differences were found among the three groups on the clinical measures used to assess symptomatic relief. The general improvement reported must therefore be attributed to nonspecific factors.