Resonance enhanced multiphoton ionization (REMPI) has been used to quantitatively detect benzene in an Ar dc plasma. The plasma reactor was fabricated from a 5 cm diam Pyrex tube that was about 30 cm long. The reactor also possessed two plasma electrodes that were separated by 3 cm. The plasma was generated at 160 mTorr pressure under continuous flow of Ar that was seeded with 100-1000 ppm of benzene. Ions generated by REMPI were detected using a separate electrode placed at the edge of the plasma zone. We were able to obtain well-resolved and unambiguous benzene REMPI spectra in the 250-265 nm laser wavelength under a broad range of plasma conditions. The spectra obtained were well resolved, exhibited sharp spectral features and were in complete agreement with the results reported in the literature under nonplasma conditions. Measured REMPI signal intensities also were linearly proportional to the benzene concentration, suggesting that REMPI can be a useful quantitative plasma diagnostic.