MRI is highly sensitive in detecting focal white matter lesions in multiple sclerosis (MS). For this reason, it has been formally included in the diagnostic workup of patients with clinically isolated syndromes suggestive of MS, through the definition of ad hoc sets of criteria to show disease dissemination in space and time. MRI is used in virtually all clinical trials of the disease as a surrogate measure of treatment response. Several guidelines have been published to help characterizing the imaging features on conventional MR sequences of "typical" MS lesions and work has also been performed to identify "red flags" which should alert the clinicians to exclude possible alternative conditions. Despite this, the application of the available guidelines and criteria in daily life clinical practice is still limited and varies among and within countries (including Italy) due to regulatory issues and heterogeneity of MRI facilities. It is crucial for neurologists and neuroradiologists to become familiar with these criteria to improve the quality of their diagnostic assessment. In patients with established MS, the main problem is to define standard procedures for monitoring the course of the disease and treatment response. This review aims at providing daily life guidelines to clinicians for a correct application of MRI in the workup of patients suspected of having MS as well as in the monitoring of disease evolution in those with established MS. It also offers clues for the standardization of MRI studies and relative reporting to be applied at a national level.