Allergic contact dermatitis (ACD) can be persistent and difficult to treat. Indeed, in ACD from chromate, less than 20% of cases are clear after 10 years. Oral cyclosporin A has been used in severe ACD. There are few reports regarding the use of azathioprine. We report two cases of ACD from chromate and two from sesquiterpene lactone which responded well to azathioprine therapy. None of the cases had responded adequately to potent topical steroids or allergen avoidance. Our cases illustrate that azathioprine 0.2 mg/kg daily is a simple, cheap and effective treatment, both in the short and long term. Azathioprine is cheaper and has fewer side-effects than cyclosporin and so may be preferable as an initial systemic therapy. Azathioprine may be effective in other forms of allergic contact dermatitis.