A 6-year-old female, shih-tzu was presented in the February with bilateral, symmetrical hair loss and hyperpigmentation on caudal dorsolumbar region. Skin test and blood examination found no remarkable finding. Histopathological examination of biopsies from the alopecic lesions revealed follicular atrophy, infundibular hyperkeratosis and some follicles were twisted truncated and dilated. The diagnosis of recurrent flank alopecia was based on clinical signs and supportive histopathology. Treatment with oral melatonin was started at 3 mg twice daily for 80 days, and by this time complete hair regrowth was observed. The following year in the September, a small non-inflammatory alopecia developed in the same site. The dog was given oral melatonin at 3 mg twice daily for 4 weeks, hair had completely regrown.