The effect of uni- and bilateral neurectomy of inferior alveolar nerve on mast cell (MC) density and topography were studied in Lewis rat gingival mucosa. The results were compared with unilateral sham operation effects. The samples were taken in each group both form left and right side of gingiva, MC were revealed by pinacyanol erythrosinate and counted in connective tissue adjacent to the basal membrane of gingival epithelium. MC were insensitive to sham operation and the differences were noted only in MC density after unilateral neurectomy between both sides of gingiva, and in distribution between the control and left side after bilateral neurectomy. The results suggests that neurectomy and sham operation trauma after 3 weeks have limited effect on mast cell density and distribution.