Restricted access materials (RAM) which allow direct injection of biological fluids in a chromatographic system were evaluated for the direct analysis of methadone (MTD) in serum by liquid chromatography (LC) and mass spectrometry (MS). Two methods were developed for the determination of methadone and its major metabolite, EDDP, in serum samples in a concentration range of 10 to 500 ng mL± 1. The first method used the single column approach with a Pinkerton GFF II (10062.1 mm ID) analytical column. In this mode, the column is the same for the sample preparation and the analysis. The total analysis time was less than 15 min with a limit of quantification of 10 ng mL11. At this level, repeatability values were 11.8% and 15.8% for MTD and EDDP, respectively. The second method used a column-switching device. A RP-4 ADS (2562 mm ID) precolumn was coupled to a LC column and achieved a total analysis time of less than 8 minutes. At the LOQ, repeatability values were 3.2% and 7.6% for MTD and EDDP, respectively. Compared to a classical liquid-liquid extraction, RAM proved to be very convenient stationary phases. Both methods a gave short analysis time with a minimum of sample handling and allowed quantitative determination of MTD and EDDP in serum.