A simple and sensitive procedure using solid-phase microextraction coupled with high performance liquid chromatography (HPLC) to analyze fluoxetine (FLU) and its metabolite norfluoxetine (nor-FLU) in plasma samples was developed and validated. SPME conditions were optimized employing a factorial design. The sampling step was performed using a PDMS-DVB fiber and desorption was carried out in a novel homemade heated interface. Fluoxetine and norfluoxetine were analyzed by HPLC, using a C18 Phase Sep column (150mmx4.6mm, 3microm) packed "in house", and acetonitrile:acetate buffer 25mmoll(-1) with triethylamine 25mmoll(-1) pH 4.6 (70:30) as the mobile phase. The developed method has shown precision, linearity, specificity, and limit of quantification (LOQ) adequate to assay fluoxetine and norfluoxetine in plasma. Furthermore, the results obtained using the homemade interface has shown an improvement in the desorption process when compared with the results obtained using the off-line mode.