The effects of liquid sugar and sucrose on several characteristic of tobacco leaves, there combustibility and harmful compound in smoke were examined. results obtained were as follows. 1) Nicotine and total nitrogen content of tobacco leaves were reduced by sugars added to tobacco. 2) Nicotine and tar transfered to smoke were reduced by 4% sugars added to burley tobacco but not reduced by sugars added to hicks. 3) pH of smoke was reduced by sugars added but pH of tobacco shreds not reduced by sugars added. 4) The filling capacity and combustibility (S. B. R.) of tobacco shreds were increased by sugars treated. 5) Nitrogen oxides transfered to smoke was reduce by sugars treated but phenols transfered was not reduce by sugar treated. 6) The capacities of moisture absorption and retention was increased by sugars treated.