This report discusses a case of a 69-year-old woman who developed chronic non-healing leg ulcers after long-term topical use of Plectranthus amboinicus. The ulcer was proven to be allergic contact dermatitis to P. amboinicus by a patch test. The ulcer healed after discontinuation of P. amboinicus. To the best of our knowledge, this is the first reported case of allergic contact dermatitis to P. amboinicus masquerading as chronic leg ulcer.