AIM　A series of 4-piperidinylthioether and sulfone derivatives of 4-［1-hydroxy-1-(2,3-dimethoxyphenyl) methyl］-N-2-(4-fluorophenylethyl) piperidine (MDL 100907) were synthesized in order to find new 5-HT2A selective ligands. METHODS　Title compounds 2a-2c were synthesized from 2,3-dimethoxythiophenol and tested for their affinities to 5-HT2A, 5-HT2C, 5-HT6 and 5-HT7 receptors and some other nervous transmitter receptors in vitro. RESULTS　Compounds 2a-2c are new compounds. The results of the binding assay demonstrated that they have relatively high selectivity for 5-HT2A receptor in vitro. CONCLUSION　Some sulfur containing analogues of MDL 100907 showed selective affinity to 5-HT2A receptor and are worth further study.