Inclusion Criteria:

Inclusion criteria for patients with atopic dermatitis:

• Outpatient at screening
• Adult male >20 years old
• Diagnosis of AD fulfilling the Hannifin and Rajka criteria
• Mild to moderate AD (Investigator Global Assessment [IGA] 2-3; localized eczema area and severity index [EASI] 1-8)
• AD affecting both arms and/or legs >10cm2 per target area
• Willing to undergo 4 mm serial punch biopsies
• Patient history of AD for at least 3 years

Inclusion criteria for healthy volunteers:

• Volunteers must be males >20 years of age
• Volunteers must be in good health, as determined by past medical history, physical examination, and vital signs

Exclusion Criteria:

Exclusion criteria for patients with atopic dermatitis:

• Concurrent diseases/conditions and history of other diseases/conditions
• Are immunocompromised or have a history of malignant disease
• Have a history of rheumatic fever, heart valve replacement, prosthetic joints or other prosthetic constituents
• Have concurrent skin disease (e.g. acne) of such severity in the study area that it could interfere with the study evaluation
• Have previously reported poor or no clinical response to topical tacrolimus ointment (Protopic®) or pimecrolimus cream (Elidel®)
• Have active skin infections
• Present with clinical conditions other than atopic dermatitis that can interfere with the study treatment
• Present with severe medical condition(s) that, in the opinion of the investigator, prohibits participation in the study
• Are maintained on emollients that contain supplementary ingredients such as urea, alpha or beta-hydroxy acids, fruit acids, vitamins A, D or E
• Have received phototherapy (e.g. UVA, UVB) or systemic therapy (e.g. immunosuppressants, cytostatics) known or suspected to have an effect on AD within 4 weeks of Visit 1 (screening)
• Have received systemic corticosteroids ([CS] e.g. oral, intravenous, intraarticular, rectal) within 4 weeks of Visit 1 (screening). Patients on a stable maintenance dose of inhaled or intranasal CS may participate
• Were treated with topical therapy, including topical calcineurin inhibitors (e.g. corticosteroids, tar) known or suspected to have an effect on AD during the current acute episode
• Were treated with antihistamines within 7 days of Visit 1
• Known serious adverse reactions or hypersensitivity to anesthetics such as lidocaine or mepivacaine
• Excluded investigational drugs/hypersensitivity
• Have received investigational drugs within 8 weeks of the first application of study drug or planned use of other investigational drugs during participation in this study
• Have known hypersensitivity to any ingredient of the pimecrolimus cream 1% or this class of study drug

Exclusion criteria for healthy volunteers:

• Erythrodermic patients, patients with Netherton's syndrome
• Personal or family history of atopy (asthma, allergic rhinitis, atopic dermatitis)
• Clinically significant findings during the physical examination
• Have a history of rheumatic fever, heart valve replacement, prosthetic joints or other prosthetic constituents e.g. lens implants or hip joints
• Volunteers with known serious adverse reactions or hypersensitivity to anesthetics such as lidocaine or mepivacaine
• Participation in any clinical trial within one month prior to current trial
• History of immunocompromise
• History of positive hepatitis B surface antigen (HBsAg) or hepatitis C test result
• Use of corticosteroids within 4 weeks prior to baseline
• Were treated with antihistamines within 7 days of Visit 1
• Phototherapy within 4 weeks prior to baseline
• Topical therapy within 5 weeks prior to the study
• Treatment with nephrotoxic drugs within 2 weeks prior to baseline (aminoglycosides, amphotericin B, colchicine)