The aim of this study was to investigate the suitability and effectiveness of heliotherapy in moderate or severe atopic dermatitis in adults in the Canary Islands. A total of 216 patients participated on 6 different 2- or 3-week heliotherapy trips. Using the Severity Scoring of Atopic Dermatitis Index (SCORAD), the severity of atopic dermatitis was assessed prior to the start of heliotherapy, after 2 weeks and then 3 months after the end of heliotherapy. A quality-of-life questionnaire was later mailed to all participants. The mean SCORAD index was reduced by 70% after 2 weeks of heliotherapy and was still 45% lower 3 months after therapy (P<0.0001). At 3 months, the use of topical steroids was still significantly reduced (P<0.0001), whereas there was no significant (P=0.1166) change in the consumption of emollients. The quality of life of patients was improved and their self-treatment and working capacity was increased. As the longer 3-week period provided no significant additional advantage over a 2-week period, 2 weeks of heliotherapy can be considered optimal. In conclusion, heliotherapy is an effective and valuable therapeutic adjunct, especially in adults with severe atopic dermatitis.