Purpose: St. John’s wort (SJW, hypericum perforatum) has a long history of medicinal use mainly for its antidepressive effect and for wound healing. However, to the best of our knowledge, this is the first clinical study evaluating the effects of topical SJW oil macerates on the intractable skin lesions of idiopathic granulomatous mastitis (IGM). Materials and Methods: SJW oil massage (two times daily for two minutes) was recommended between 2016 and 2019, only for patients with persistent or intractable skin lesions, after complete regression of granulomatous mass with two cycles of high-dose oral steroid and empiric antibiotic. Skin lesions were assessed and graded before and after treatment, as clear, mild, moderate and severe. A mini-questionnaire was also filled in for each patient at the end of six-week treatment. Results: A total of 21 patients with persistent IGM lesions used SJW oil after completion of the standard treatment protocol. All patients were women, and the mean age was 36.6 years. Hyperemia (100%), scaling (61%), induration (52%) and ulcer (28%) were the predominant skin lesions, Distribution of the lesions according to the degree of severity were as mild, moderate and severe, and seen in 35%, 41% and 23% of the patients, respectively. When compared with pre-treatment scores, there were very significant regression (clear: 76.4%, mild: 17.6%, moderate: 3.9%, severe: 1.9%; p<0.001 for each). The overall success rate (total clearance plus mild signs) of treatment was 94%. Conclusion: SJW oil massage seems to be very effective in patients with IGM-related persistent skin lesions.