The molar mass distribution of polyethylenes synthesized at pressures up to 2500 bar and temperatures to 255°C with thermal and partly with photochemical initiation is determined by GPC. In the limiting situation of high pressure, low temperature, and small conversion a distribution function based on a limited set of kinetic equations provides a fair representation of the experimental data. The transfer constant with the monomer is derived as a function of pressure and temperature. The logarithmic normal distribution reasonably represents the molar mass distribution of the high pressure polyethylenes if the conversion is low and if both empirical parameters are taken as temperature dependent. The degree of long chain branching is analyzed for the ethylene polymerization as a function of pressure and temperature and to maximum conversions of 30%. It turns out that even at conversions as low as 2% long chain branching is not negligible.