This study examined the therapeutic effects of aromatherapy for the treatment of otitis externa in dogs. Eleven dogs with otitis externa were examined. The control group (5 dogs) was treated with susceptible antibiotics, and the experimental group (6 dogs) was treated with aroma-oil applied topically to the ear canal. The aroma-oil contained 10 ml sweet almond oil, 0.3 ml bergamot oil, 0.2 ml lavender oil, 0.1 ml tea tree oil and 0.1 ml roman chamomile oil. The blended aroma-oil (0.1 ml) was applied to the ear canal twice daily for 2 weeks. The authors examined the changes in the clinical signs, bacterial count in discharges, total WBC count and neutrophil/lymphocyte ratios in the two groups. The bacterial cell counts in the experimental group were significantly lower at one (p less than 0.01) and two weeks (p less than 0.05) after treatment than the control group. These results suggest that aromatherapy is an effective and practical treatment for otitis externa in dogs.