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Fishing activities,species composition,seasonal availability,distributions and importance of mud crab fisheries were studied in Pak Phanang mangroves,Nakhon Si Thamarat,Thailand.The study was conducted from May 2006 to May 2007 to reveal the present status,the role of mud crab fisheries to local level and some biological aspects for better management of this valuable resource.With the questionnaire survey and group discussions,samples were taken from the local fishermen as well as local traders to accomplish the mentioned purposes.There were 95 ％ people in the fishermen colony that formed inside of the mangroves,solely depended on mud crab fisheries.Three mud crab species recorded from the study area in which Scylla olivacea and Scylla paramamosain formed 46％ and 40％ of total specimens,respectively.The third species S.serrata was noticed in each sampling time but in small numbers.In the dry season,S.paramamosain harvested higher than S.olivacea which showed higher in monsoon.In samples,males outnumbered females by 1 ∶ 0.96.Sample crabs were ranged carapace width of 50-130 mm with body weight of 25-490 g,while 80％ population was within the carapace width of 75-105 mm.The total annual catch and monetary value ranges were 113-188 tons year-1 and US($)1.71-2.85 million respectively that represent the production ranged of 16-20 kg · h-1.With the increasing fishing pressure and environmental pollution,mud crab resource has declined from earlier period but still crab fishing is a major source of food and prosperity to the local people.