This investigator-blinded study is designed to assess whether the order of application affects the efficacy of the combination treatment Clobex® Spray (clobetasol propionate) and Vecitcal® (calcitriol) Ointment in plaque psoriasis.

This is an investigator-blinded, bilateral comparison study. A total of up to 12 subjects with mild to moderate plaque psoriasis will be enrolled in this study, so that at least 10 subjects complete the 4 week trial. These 12 subjects will receive the combination therapy of Clobex® Spray and Vectical® Ointment to treat their psoriatic lesions (except those on the scalp, face, groin, axillae or other intertriginous areas). Half of the subjects will first apply the Clobex® Spray followed by the Vectical ointment to lesions on the right side of their bodies, and Vectical® Ointment first followed by Clobex® Spray to the lesions of the left side of their bodies. The other half of the subjects will first apply Clobex® Spray followed by Vectical® Ointment to the lesions of the left side of their bodies, and Vectical® Ointment first followed by Clobex® Spray to the lesions on right side of their bodies. Treatment will be applied twice daily for 4 weeks. One target area on each side of the subject's body will be chosen for target lesion assessment.

All subjects will be consented prior to any study evaluations/procedures. Study evaluations including Target Lesion Severity Score (TLSS) and photography will be performed at Baseline/Day 0, week 2 and week 4.

Inclusion Criteria:

1. Subjects must be at least 18 years of age and in good general health as confirmed by a medical history.
2. Females of childbearing potential must have a negative urine pregnancy test on Baseline/Day 0 and must agree to use adequate birth control methods during the entire study (a barrier method {condoms, diaphragm}; hormonal contraceptives {birth control pills, implants [Norplant] or injections [DepoProvera]}; intrauterine device {IUD}; or abstinence {no sexual activity}).
3. Subjects must be diagnosed with plaque psoriasis affecting < 20% body surface area, with at least one discreet plaque on the each side of the body (excluding the face, scalp, groin, axillae or other intertriginous areas).
4. Subjects must have at least 2 lesions suitable for evaluating response to test agents (one on the right side and one on the left side of the body). The severity of the disease for each target lesion at Baseline/Day 0 must be rated at least 2 (Mild) for each of the key psoriasis characteristics (scaling, erythema, and plaque elevation).
5. Subjects must be able to understand the requirements of the study abide by the restrictions and return for the required examinations.

Exclusion Criteria:

1. Female subjects who are pregnant, nursing or planning a pregnancy during the study.
2. Subjects with known hypersensitivity to any components of the test medication.
3. Subjects with non-plaque psoriasis (e.g. guttate, erythrodermic) or other related diseases not classified as plaque psoriasis.
4. Subjects whose psoriasis involves only the scalp, face, groin, axillae, and/or other intertriginous areas.
5. Subjects who have surface area involvement too large (>20% BSA) that would require more than 59 ml/week (50 g/week) of Clobex® spray and/or more than 200 g/week of Vectical® ointment.
6. Subjects requiring any other medication (topical or systemic) that may affect the course of the disease during the study period as determined by the study investigators.
7. Subjects using biologics or any other systemic treatment (e.g. immunosuppressants, acitretin) for psoriasis within 12 weeks of entering the study.
8. Subjects using systemic corticosteroids within 28 days of entering the study
9. Subjects using topical corticosteroids or other topical therapies (other than emollients) at the target area locations within 2 weeks of entering the study
10. Subjects using phototherapy (UVB, PUVA) within 4 weeks of entering the study.
11. Subjects with overt pre-existing telangiectasias or skin atrophy at intended treatment sites (target areas).
12. Subjects with intakes of more than 2,000 IU/day (50 mcg/day) of vitamin D (tolerable upper intake level) and/or more than 1,000 mg/day of calcium (based on Dietary Reference Intakes developed by the Institute of Medicine of the National Academy of Sciences).
13. Subjects who have participated in another investigational drug or device research study (at the target areas) within 30 days of enrollment.
14. Subjects who are using any medication or has any disease which in the judgment of the investigator will interfere with the conduct or interpretation of the study.