Abstract: An EXCEL program for data processing and quality evaluation in determination of volatile organic compounds and polycyclic aromatic hydrocarbons in groundwater by gas chromatography-mass spectrometry (GC-MS) based on the Macros (VBA) was completed. The program provides the functions of source-data gathering from an Agilent 6890-5973N GC-MS, qualitative identification of compounds, calculation of results and reversibly dealing with incorrect confirmed data based on Q-value limits (as a measurement of qualifier ratio). The program also provides the functions of statistics and evaluation for various quality control indexes, such as laboratory reagent blanks, field reagent blanks, reproducibility deviations of laboratory duplicates, recovery of standard addition of the samples, recovery of quality control samples and long-term performance of the analytical method. It also provides functions of forming quality control reports and transferring the data to a database.