In the Betts process for electrolytic refining of lead, adhesion of anode slime onto anode surface is practically very important. This investigation was undertaken to reveal dominant factors governing adhesiveness of the anode slime. The results are summarized as follows: the adhesiveness depends considerably upon the form and the physical state of impurities present in the anode, which can be classified into three types,viz, solid solution, precipitation, and eutectic type respectively. Solid solution types give the best adhesion. Precipitation type shows better adhesion than eutectic type. Eutectic type slides off the anode easily. The adhesion is also largely affected by the heat treatment of anode. For eutectic type, water quenching is effective to increase the adhesion. I also confirmed that the slime adhesion can be improved by the addition of elements which form inter metallic compounds with eutectic type of impurities.