Mangrove forests within a macrotidal embayment, Creek 'H', East Arm, in Darwin Harbour, northern Australia, can be divided into a number of assemblages corresponding to geomorphologically defined habitats. The most widespread of these are: (i) tidal creek, dominated by Camptostemon schultzii, Rhizophora stylosa and Bruguiera parviflora, with occasional massive Avicennia marina; (ii) tidal flat, dominated by mixed Ceriops tagal var. australis and Bruguiera exaristata; and (iii) hinterland margin, with a gently inclined colluvial substrate, dominated by almost monospecific Ceriops tagal var. australis. The average annual litter fall was estimated from two years of observations at a series of locations. The highest rates of litter fall, > 1000 g m-2 year-1 (dry weight), were recorded in tidal creek mangrove forests, with litter fall beneath 13 m tall Avicennia marina of 1400 g m-2 year-1. In tidal flat, mixed Ceriops tagal/Bruguiera exaristata litter fall was 745 g m-2 year-1, with approximately equal contributions from both species. In hinterland margin, litter fall varied between 686 g m-2 year-1 beneath taller Ceriops (up to 7 m) and 300 g m-2 year-1 beneath lower Ceriops (< 2 m). All locations showed seasonality of litter production with peak fall in the wet season (December-May), but the proportions and nutrient content of components varied from species to species and site to site. Despite the tropical location (12°30'S) and large tidal range (up to 7·8 m), litter fall is not especially high compared to other mangrove forests and shows considerable spatial variation. Leaf litter was generally low in nitrogen (N) content ( 0·8%). Nitrogen and phosphorus showed marked decreases (ca. 50%) from green to senescent leaves on the tree, presumably as a result of nutrient translocation, but the percentages of these nutrients subsequently increased in litter from traps. © 1988.