Introduction: the host’s salivary enzymes have been proposed as diagnosis bio-markers at a periodontal stage. The concentration of salivary alkaline phosphate (sap) has been associated with gum disease (gd). Objective: the purpose of this article is to determine the possible relation between sap levels in saliva and probing depth. Material and methods: 90 patients, all systematically healthy and with periodontitis, were divided in two groups: g1, 45 patients with periodontal pockets of 4-5 mm in depth, and g2, 45 patients with 6 mm o more in depth. The levels of sap (ui/i) in the saliva were evaluated through a spec-trophotometer at 520 nm. Results: the average concentration of sap in saliva was higher in g1 when compared to g2 (p > 0,05). Person correlation test showed a significant relation between concentrations of sap in the saliva and depth of the catheterization (p  >  0,05). Conclusion: the assessment of sap in saliva may become practical and reliable to the detec-tion of activity and severity of gd.