Tacrolimus is the first T-cell selective immunosuppressive agent with demonstrated topical applications. The Food and Drug Administration recently approved topical tacrolimus ointment with an indication for treating atopic dermatitis in patients as young as age 2 years. In clinical trials, significant absorption did not occur through intact skin and rarely occurred through dermatitic skin. Detectable blood levels diminished as the skin improved. In phase 3 atopic dermatitis trials lasting more than 3 years, reported adverse effects have been minor. Recipes have long been available for compounded formulations similar to the proprietary agent. This case report is another example of compounded tacrolimus ointment used with success for a difficult-to-treat inflammatory cutaneous problem. Other reported uses include pyoderma gangrenosum, cutaneous Crohn disease, and ichthyosis linearis circumflexa. However, uncontrolled enthusiasm for this drug must be tempered with the caution reserved for any medication that has a wide range of systemic adverse effects, especially when prescribed for infants, young children, and patients with a widespread skin disease that features very poor skin barrier function.