The clinical, gross, light microscopic and immunohistochemical findings of three cases of blue nevus of the uterine endocervix were described. All three cases were incidentally found in hysterectomy specimens from middle-aged women, 45 to 48 years of age. The lesions were small and measured 1 to 4 mm in the greatest diameter. The presence of elongated, somewhat wavy and dendritic melanin-containing cells, in clusters or scattered deep in the subepithelial stroma and between the endocervical glands, was the distinct feature. The cytoplasmic granules appeared black with Grimelius and Fontana-Masson stains. The cells showed strong positive reaction with S-100 protein in perinuclear cytoplasm, in addition to the diffusely dispersed melanin granules. The demonstration of S-100 protein in the blue nevus, along with the histochemical findings, supports combined melanocytic and schwannian differentiation of the blue nevus cells.