Invertebrate collections were made at 32 sites within a 6 ha area of inter-tidal mud sediments around the effulent outfall from Ashton paper mill; additional samples were collected for physico-chemical analysis. Seventeen taxa were recorded and invertebrate density varied between 1,580 and 32000 per m. There was no evidence that the effulent caused an increase in the organic content of the sediments although there were local reductions in redox potential. Other physico-chemical characteristics of the sediments were relatively uniform and the effulent did not have any discernable effects on the macroinvertebrate fauna, the communities around the outfall being similar to that occurring more extensively in this area of the Severn Estuary.