Psoriasis is a chronic inflammatory skin disease with a high social and psychological impact on the quality of life of patients. Tomesa balneophototherapy is based on bathing in a magnesium-rich salt solution combined with exposure to narrowband ultraviolet B phototherapy. We conducted a retrospective clinical trial on 174 patients affected by mild to severe psoriasis undergoing Tomesa balneophototherapy. The basal course consisted of three to five sessions per week for a total of 30 sessions. Subsequently, patients could continue with a maintenance course of one session per week for a total of 30 sessions. We recorded a significant reduction of the mean Psoriasis Area and Severity Index (PASI) index with an achievement of at least PASI 75 in 52.1% of the 119 patients who completed the basal course and an improvement of the ‘quality of life’ of patients. The good efficacy obtained by this treatment, and the psychological impact on the quality of life of patients, demonstrated that Tomesa balneophototherapy could be a good option for the treatment of a chronic disease associated with psychological distress, like psoriasis.