During this decade, shrimp culture has been developed extensively in the coastal areas of Thailand leading to decrease in mangrove swamps and productivity in these areas. Furthermore, it causes organic enrichment at the bottom of the ponds and adjacent coastal areas when the waste water is discharded from the farms. To understand the meiofauna community under such conditions, sediment samples were collected from shrimp culture ponds in Ranong and Phang-nga provinces, in the southern part of Thailand thoughout one cycle of culture from April to October 1995. Meiofauna density ranged from 14 to 2,299 ind. 10 cm-2 with the lowest density at the beginning of culture activity. Free-living marine nematodes were most dominant accounting for between 63 to 100 % of total meiofauna density. Harpacticoid copepods and rotifers occurred occasionally. Density of nematodes ranged from 14 to 2,168 ind.10 cm-2. Shannon-Wiener diversity values were low at all sampling stations ranging from 0.8 to 1.5 with evenness values from 0.13 to 0.94. There were clearly particular dominant species, namely, Theristus longisetifer, Diplolaimella thailandica, Prochromadorella macrocephala, Thalassomonhystera siamensis and Chromadorina sp. The former four species are new to science. Their taxonomic description are also presented. Environmental factors in the shrimp culture ponds are also reported.