A comparison between the Manchester System and the Paris System of interstitial dosimetry has been made in the case of single and double plane implants. The rules of both systems are reviewed. A brief description of the Paris System is presented in an appendix. Dose distributions for two different examples are presented in two orthogonal planes. The Paris System uses considerably fewer sources than the Manchester System. It results in a larger volume of high dose than the Manchester System. The use of Iridium-192 sources strength and source length can be adjusted represents a significant advantage. The Paris System attempts to adapt the implant configuration to the clinical situation as the target thickness is used to define the source separation and the target length is used to define the source length. The differences in the dose definition are discussed.