Rio del Rey Estuary mangroves are the most widespread in Cameroon but remain poorly known. This study aims to determine changes in the floristic composition and structure. The survey was conducted in seven localities of the SW region. Transects were opened perpendicular to the main tidal channels. Sampling plots (25 m x 25 m) were established to evaluate the structure of the vegetation. All African Atlantic mangroves characteristics species are present. Rhizophora spp. predominate as in most African stands. Floristic diversity was low and varied according to localities. The Shannon diversity index H" ranged from 0.34 to 1.91 and the Margalef specific richness index varied from 1.08 to 4.45. The mean diameter was 20.38 ± 18.79 cm; and trees height ranged from 3.82 to 37 m. The absolute density was 934.19±564.88 stem ha^-1 and the basal area was 1.54±0.99 m² ha^-1. In many cases, the diameter class distribution has shown characteristics of disturbed stands. The Newman-Keuls test has shown differences between plots. The sample unit sizes, the degree of vegetation evolution, the Nypa fruticans invasion and the anthropogenic activities extent affect significantly the characteristic of mangrove stands.