Our previous research showed that, in a mice tail model for psoriasis, topical celecoxib might have an antipsoriatic effect in vivo by increasing granular layer development. The aim of the present study is to assess the effect of three celecoxib concentrations using a mice model for psoriasis. Topical application of celecoxib (2%, 4% and 8%), with two negative controls (untreated and white soft paraffin as ointment base) and one positive control (tretinoin 0.05%), was performed for two weeks. The effect on granular layer development and epidermal thickness was measured on hematoxylin-eosin staining. The morphometric assessment was made by using mean orthokeratosis degree and mean epidermal thickness as main parameters. All celecoxib concentrations have significantly increased the mean orthokeratosis degree as a marker of an anti-psoriatic effect. Celecoxib 8% and 4% lead to a statistically significant increase in orthokeratosis degree when compared with celecoxib 2% and tretinoin 0.05%. Along with cyclo-oxygenase inhibition, other mechanisms of action of celecoxib are discussed. This study offers valuable information for future clinical trials with celecoxib as a topical anti-psoriasis agent.