Objective To analyze the withdrawal reason of natalizumab in depth based on the serious adverse reaction reports and approval channel, and to provide decision references for more safe and effective report method of other biologicals. Methods We searched MEDLINE, EMbase, and the official websites of Food and Drug Administration (FDA) for case reports, approval channel, and the relevant information of drug marketing or withdrawal. Results Four case reports and fourteen official reports were included. Three cases of progressive multifocal leukoencephalopathy (PML) were reported in the clinical trials after natalizumab’s initially approval with two dead and one disabled, which could be retrieved by hemodialysis (2 cases hitherto). Consequently, multiple sclerosis (MS) patients were willing to bear the risk. Two cases of natalizumab-related PML (0.06‰) were confirmed in 32 000 patients without death report after two years of its remarketing, in July 2008. Another PML patient was reported in October 2008. Because of its non-substitutability for treating MS and Crohn disease (CD), FDA announced that patients could still use natalizumab under the close monitoring. Conclusion (1) The most serious adverse reaction of treating MS and CD with natalizumab is PML, but it can be preventable and curable now. The monitoring findings of efficacy and adverse reaction during the postmarketing indicate that the review system is perfect and practicable relatively, and can give references for other high-risk drugs on the fast or standard approval channel, for example, Chinese medicine injection can draw lessons from it. (2) The remarketing of natalizumab not only provide significant risk management precedent for other drug-development firms, but also brings hope to the remarketing or relaunching clinical trials for the suspected sideeffect drugs. (3) Because of the fast-track reviewing of natalizumab and the overlap between the research of Good Clinical Practice (GCP) and the post-marketing evaluation, we should continue to track the information and provide new evidence.