Two β-N-acetylglucosaminidases (EC 3. 2. 1. 30. ) were isolated from rat uterus, The two enzymes were separated by DEAE-cellulose column chromatography after (NH₄)₂SO₄ fractionation. One of them has been called A form because of its heat-labile property, while the other B form because of its heat-stability. The A form was purified by Sephadex G-200 chromatography, The B form was further purifiid by DEAE-cellulose and Sephadex G-200 chromatography. The A form had optimum activities at pH 4.7 and B form at pH 4.3. The Km value was 3.64 mM for A form and 0.4 mM for B form, The A form showed optimum activities at 37℃ while the B form showed at 55℃. Sulfate, sulfite, and acetate inhibited A form enzyme, but Zn^(2+), Mg^(2+) and phosphate activated the A form enzyme, The purified A form lost its activity rapidly at 50℃ after 30 min preincubation, but the B form retained 62 % of its activity at the same condition.