Canned motor pumps (CMPs) are completely leak-proof and compact sealless design, finds wide scope in modern industries for handling toxic liquids. CMP is an integral combination of conventional centrifugal pump and induction motor. CMPs are intentionally designed for very high reliability by minimizing vibration & noise level as compared to conventional centrifugal pumps. In this paper, detailed rotordynamics & key vibration sources for CMPs are discussed. CMPs vibration monitoring method and spectrum analysis for fault diagnosis and subsequent remedies are also discussed to mitigate primary low vibration requirement. Pump rotordynamics has presumed a major role in deciding pump reliability. To avoid resonance, sufficient margin should be provided between rotor critical speed & exciting frequency. For rotor stability, the design of hydrodynamic fluid film bearings shall be tuned to avoid sub-synchronous whirl & whip by lowering cross coupling vector than damping vector. In forced vibrations, mechanical & hydraulic imbalance, vane pass pressure pulsation, cavitation, internal water recirculation, excessive bearing clearance, eccentric rotor and broken or loose rotor bars are the key sources of vibration. The severity of each vibration source needs to be mapped. In lieu of direct shaft displacement measurement with proximity probes, vibration monitoring with accelerometers at radial bearing housing can also identify potential vibration problems accurately using FFT spectrum analysis. Case studies have been discussed to diagnose faults such as mass imbalance, whirl instability and excessive bearing clearance in CMP from frequency spectrum analysis. In nutshell, low vibration & silent CMPs are possible solely by addressing significant vibration sources through optimal hydraulic, mechanical and electrical design.