The design of PCM regenerators for crosstalk limited environments is considered. A Regenerator Noise Figure is introduced and used to compare various regenerator equalizer designs. An optimum equalizer is derived to provide a basis for the comparison. The major conclusion is that cosine rolloff equalizers provide better crosstalk tolerance than Gaussian equalizers and that with particular rolloff factors they achieve near optimum performance. AMI, HDB3, and Class 4 partial response line codes are considered and results placed into practical context by examining regenerator eye diagrams.