The protective effects of deflazacort against the inflammation that follows the conjunctival provocation test (CPT) by specific allergen were assessed in 24 patients with rhinoconjunctivitis caused by Parietaria judaica in a double-blind study. After a screening CPT, patients were randomized into four treatment groups, each being given deflazacort (oral tablets) at 6, 30, and 60 mg once daily, or matching placebo, for 3 d, outside the pollen season. Clinical evaluation (itching, hyperemia, lacrimation, and swelling of eyelids) and cytologic assessment (number of inflammatory cells in conjunctival scraping and evaluation of ICAM (intercellular adhesion molecule)-1/CD54 expression on epithelial cells) were performed at base line, 30 min (early-phase reaction (EPR), 6 h and 24 h (late-phase reaction (LPR)) after specific CPT, and before and after treatment. Neither the EPR clinical reactions nor the EPR total number of inflammatory cells was modified by deflazacort. However, the LPR clinical effects were significantly reduced by deflazacort at 30 or 60 mg/d (P < 0.01), as compared with placebo. The total number of inflammatory cells during LPR was significantly reduced by deflazacort at 30 or 60 mg/d (P < 0.01), as compared with placebo. Furthermore, CD54 expression was significantly reduced by deflazacort at 30 or 60 mg/d both in the EPR (P < 0.01) and LPR (P < 0.01), as compared with placebo. None of the studied indicators were modified at the 6 mg/d dose. This study shows that deflazacort has a highly protective action against clinical and cellular LPR effects induced by the specific CPT. In addition, deflazacort markedly reduces CD54 expression on the conjunctival epithelium during both EPR and LPR.