A near-infrared (NIR) spectroscopy technique for the control of lactic acid fermentation process has been proposed. Lactic acid, glucose, and biomass concentrations were determined by the NIR spectroscopy method. The three parameters examined were closely correlated to the results obtained with classical laboratory procedures. Moreover, the conditions for the on-line utilization of the NIR spectroscopy measurement system were pointed out. The great versatility of the NIR spectroscopy should permit its use for other fermentation processes.