ABSTRACT
With the increasing demand to study the cause of complex diseases, mega cohort has gradually replaced the traditional small sample cohort and become the hotspot of epidemiological research. Follow-up is the essential step in a cohort study to obtain the information about the onset and death of diseases, migration or loss of follow-up of the cases. Its quality has a direct impact on the conclusions of cohort study. Therefore, it is necessary to develop a reasonable follow-up monitoring program for a mega cohort.In this paper, we summarized the contents and methods of the follow-up monitoring program in the mega cohorts at home and abroad, which aimed to provide suggestions for the new cohort and improve the follow-up program for the existing cohort.