Near-infrared spectroscopy (MR), a nondestructive analytical technique, was employed for the simultaneous determination of the concentrations of glucose and lactic acid in peritoneal dialysis solutions. Solutions mere placed in a near-infrared spectrophotometer and the absorbance at wavelengths between 400 and 2500 nm was measured at 2 nm intervals. To obtain calibration equations, multiple linear regression (MLR) mas carried out on the NIR spectral data and on the glucose and lactic acid concentrations obtained by enzymatic methods using a calibration sample set. The value of the simple correlation coefficient (r) was 0.996 when using a wavelength of 2270 nm for glucose. The value of the multiple correlation coefficient (R) for lactic acid mas 0.997 when using wavelengths of 1688 and 1268 nm. To validate the calibration equations obtained, glucose and lactic acid concentrations in a prediction sample set which was not used for calibration were calculated using the calibration equation and compared with the concentrations measured by the enzymatic method. Excellent agreement between the results of the enzymatic method and of NIR was observed for both constituents. Con centrations of glucose and lactic acid in the peritoneal dialysis solutions were analyzed simultaneously by NIR. The procedure for NIR was simple, and the operation time required to determine the concentrations was a few minutes. These results indicate that NIR may be a useful method for monitoring of the production of peritoneal dialysis solutions.