Corticosteroids, as reported above, in the form of a nasal spray are the first-line treatment for perennial allergic rhinitis; one of the most widely used is mometasone furoate. A meta-analysis of randomized, double blind, placebo controlled, clinical trials on mometasone furoate nasal spray in the treatment of allergic rhinitis, by a comprehensive search of the MEDLINE, LILACS, SCOPUS, and the Cochrane Library databases up to 31 October, 2007 was carried out. Meta-analysis was performed with the random or the fixed effect models depending on heterogeneity, by using revman 5 software on the sixteen of the 113 identified articles that met the inclusion criteria. This meta-analysis provides a level Ia evidence for the efficacy of MFSN in the treatment vs placebo, with adverse events frequency similar in both groups.