Abstract: A molecularly imprinted solid-phase extraction (MISPE) procedure based on precipitation polymerization was developed for the simultaneous extraction of dexamethasone (DM) and its structural isomer, betamethasone (BM), from biological matrices. A DM-imprinted polymer was synthetized using methacrylic acid as monomer and divinylbenzene as cross-linker, and the porogen was a mixture of acetonitrile and toluene (3:1). After removal of the template, loading, washing and elution steps were optimized. The maximun recovery of DM and BM was achieved when loading with toluene and washing with 5% acetonitrile in toluene, and eluting with 1% acetic acid in methanol.