We developed a method of rapid assay for biochemical properties of the saliva based on attenuated total reflection infrared spectroscopy. This method allows evaluating saliva composition within 5 min without sample preparation; 10 microl sample is enough for the analysis. The concentration of total protein, glucose, secretory immunoglobulin A, urea, amylase, cortisol, inorganic phosphate in the saliva can also be measured. Precision and reproducibility of the evaluated parameters are comparable to those obtained by routine clinical analysis.