A study was conducted to evaluate the shrimp trawl fishery in the seas off Negombo and Hendala during the period January 1998 to December 1999. In the shallow seas off west coast trawling is conducted by two types of crafts viz. 3.5 t wooden boats (mechanised trawls) and traditional sail driven large dug out canoes (non-mechanised trawls). The total catch effort and the catch per unit effort showed seasonal variations. A seasonality in the trawl fishery was observed with a peak period from June/July to October/November, which apparently coincided with the south west monsoon and the inter monsoon periods of the island. The statistical analysis indicated that the catch rates of both craft types observed during the south west monsoon were significantly higher than during north east and inter monsoon periods (P<0.05). There is no substantial difference between the estimated mean catch rates for the two craft types for the two years study. The estimated annual fish productivity of the non-mechanised and mechanised trawls were 390 and 208 MT in 1998 and 403 and 259 MT in 1999 respectively. Penaeid shrimps formed 60-64% of the catch of the west coast trawl fishery. Trawl by-catch mainly consisted of sea crabs, sciaenids, leiognathids and Opisthopterus tardoore. The shrimp : by-catch ratio for the trawl operations in the study area were estimated at 1 : 0.67 for non-mechanised trawls and 1 : 0.56 for mechanised trawls. The estimated mean income per trawl operation varied from Rs. 930 to 2,960 (Mean = Rs. 1,660) for non-mechanised trawls and from Rs. 470 to 4,240 (Mean = Rs. 1,860) for mechanised trawls.