A fiber coated by polyaniline (PANI) was obtained through electrochemical deposition and applied for solid-phase microextraction (SPME). The same method was applied for the preparation of an SPME fiber coated by a PANI/multiwalled carbon nanotubes (PANI/MWCNTs) composite. The prepared fibers were employed for extraction of methylenedioxymethamphetamine (MDMA) hydrochloride from aqueous and chloroform samples. The resulting substances were analyzed by gas chromatography-mass spectrometry. The developed method proved to be simple with high reproducibility. The amount of extracted MDMA hydrochloride from aqueous solution and MDMA from chloroform solution by the PANI/MWCNTs fiber was about 3.5-fold and 2-fold that of the one without CNTs. It could be suggested that the composite material with CNTs has both an augmented surface area and an elevated adsorptive capacity which lead to the increased extractive capacity for MDMA.