The installation of the Muon Barrel chambers in the five wheels of the
CMS detector was started in 2005. All chambers are equipped with their
MiniCrate, where the control electronics, the readout boards, and local
trigger electronics are housed. Every chamber has to be commissioned,
both by testing the electronics of the MiniCrate and by looking at
cosmic-rays, triggered by the chamber itself. I will describe the
commissioning procedure, namely, the tools and method to test the
behaviour of the chamber, and report on detected problems and chamber
performance.