This content was analysed in patients with chronic periodontitis and in control subjects. In periodontal disease, it was characterized by higher mean concentrations of glycine, proline, tyrosine and delta-aminovaleric acid than in controls (p less than 0.001). However, the range of values varied considerably in the two groups. There were differences between periodontitis and control samples in the proportions of proline to serine (p less than 0.01) and proline to glutamic acid and glutamine (p less than 0.05). Bacterial contamination and decomposition of salivary proteins is responsible for the elevated salivary levels of glycine, proline, tyrosine and delta-aminovaleric acid in the periodontal group.