Spatial and temporal variations of the demersal fisheries resources of Malaysia were studied using multivariate analysis of their abundance (biomass) from research trawl surveys in relation to geographical and environmental parameters. TWINSPAN results indicate that the demersal resources of Malaysia can be geographically divided into five major species assemblages. Two assemblages are in Peninsular Malaysia and three assemblages are in Sabah and Sarawak waters. In general the demersal resources can be grouped into three types: assemblages associated with coastal/mangrove communities, with the offshore (deepwater) ecosystem and an intermediate assemblage. The coastal assemblage is found in shallow coastal waters, less than 40 m depth, while the offshore assemblage is beyond the 90 m depth range. The intermediate assemblages occur between 40 to 90 m depth. Intermediate assemblages were observed in the entire peninsula of Malaysia. A coastal assemblage was also found on the West Coast of Peninsular Malaysia. The Sabah and Sarawak waters were characterized by all three types of demersal assemblages. Salinity and temperature were noted as the environmental parameters that influence the delineation of the species assemblages geographically. In terms of temporal variation, two periods in relation to the monsoon were recognized, the pre-monsoon period and the post-monsoon period, separated from each other in July.