β-1,4-endoglucanase(EC 3,2,1,4) was isolated and purified from Nicotiana tabaccum L. Var. Virginia 115 suspension cultured cells. The molecular weight as estimated by Sephadex G-100 was about 14,000. The optimum pH for activity was 5.4. The Km value for carboxymethyl cellulose was 0.18 ㎎/unit and the enzyme was quite resistant to heating. Polyamine did not affect the activity of β-1,4-endoglucanase in vitro but the activity increased drastically when polyamines were added in the suspension culture medium. It is suggested that increase in β-1,4-endoglucenase activity due to polyamine might be related to growth of the plant.