The distribution and dynamics of phosphorus have been studied in the mangroves of Sepetiba Bay, Brazil. Leaf fall contributes 3.0 kg P ha−1yr−1 to the sediment. The total above ground biomass of the R. mangle stand was about 65.3 t ha−1, the P accumulation was 3.9 kg P ha−1 where 63% of the total P-biomass was accumulated in the leaves. The biomass of below ground roots was about 8.2 tha−1 and accumulated 16% of total P-biomass. Sediment contained 452 kg P ha−1 where P combined with calcium (P-Ca) was the main fraction (260 kg ha−1). The annual flux of P as litter fall was small (< 1%) compared to total P in the sediment reservoir. The annual export of P by macrodetritus corresponds to 0.05% of the total sediment reservoir.