Benthic infaunal communities at Mai Po Inner Deep Bay mudflat, Hong Kong were investigated between August 2002 and August 2003. A total of 55 species belonging to 8 Phyla from more than 99,074 specimens were recorded. The species richness varied between 13 at Station B in August 2002 and 28 at Station D in August 2003 with an average of 21 across the mudflat and the species diversity was low [H'(log₂) = 0.7-3.5 with an average H' = 2.4]. Seasonal variations were also observed through abundance and biomass across the mudflat among the seasons. The abundance density was between 8,977 individuals m-² at Station D in February 2003 and 77,256 individuals m-² at Station B in November 2002 and the overall average density was 25,274 individuals m-² for the four stations. The benthic infauna were dominated by pollution tolerant species at this wetland mudflat.