Near infrared spectroscopy (NIR) was employed to predict the concentrations of the nutrients, glucose and glutamine, and the products, lactic acid and ammonia, in the culture broth of a mouse-mouse hybridoma. A supernatant of the culture broth was supplied to a near infrared spectrophotometer and the absorbance at wavelengths between 1,100 and 2,500 nm was measured. The correlations between the concentrations obtained by conventional methods and those obtained by NIR were examined by multiple regression analysis. NIR values predicted by 5-wavelength regression were in good agreement with those obtained by the usual methods. The multiple correlation coefficient was over 0.98 for all four substances. The procedure involved in NIR is simple, and the operation time required to predict the concentrations is only 5 min. The results suggest that NIR is a useful method for the control of animal cell cultures.