Spectroscopic trace-level detections (as low as 1 x 10(-11) M) of procaine using surface-enhanced Raman scattering (SERS) technique and utilizing silver nanoparticle (Ag-Np) substrates were successfully accomplished. Significant intensity enhancements of the Raman bands associated with -C=O stretching, -C-N stretching and -NH2 bending vibrations were observed. Possible modes of SERS interaction between the procaine molecule and Ag-Np were investigated theoretically, and the results were found consistent with experimental data. The intensities of SERS band at 1607 cm(-1) were successfully correlated with the concentrations of procaine solutions. The present approach exhibits a high sensitivity and low limit of detection.