A DNA polymerase-template complex found in mouse Erhlich ascites tumor cells was purified by twice discontinuous gradient centrifugations and agarose gel filtration. After purification, the specific activity of the complex increased about 500-fold. The size of the complex was found to be 510,000 daltons. The shape of the complex was globular under electron microscope. Its diameter was between 100-110 A. The complex was isolated into two main enzyme proteins and a homogeneous DNA template by DEAE cellulose chromatography. The main enzyme had a molecular weight of 300,000 daltons and a sedimentation coefficient of 9.5s. The endogenous template DNA showed a single zone in polyacrylamide gel electrophoresis analysis. The sedimentation coefficient was determined to be 3.8s.