Rodents are distributed in all continents except Antarctica,and they are also adapted to habitats in cities.Controlling rodents in the megalopolises has become an important topic for public health.Three topics were covered in the study: rodent invasion in the rail transit system,application of biological sterilization and rodenticides for urban rodent control,and rodent control in the mega events (e.g.Shanghai EXPO) .The rail transit system is an important part of urban transportation,rodents can cause damage which leads to transit malfunctions.Rodent invasions were investigated in the Shanghai rail transit system.Visual observations of standardized areas (15m2) ,either with or without food lures present,showed evidence of rodent activity (3.8%and 9.8%respectively) .Rodents have already become a problem in the Shanghai rail transit system.A new biological sterilizing agent was evaluated for rodent control in urban areas.This agent was applied several times within a subdistrict and the results showed a better long term effect over 2 years than if anti-coagulant rodenticide was used.Mega events in some megalopolises,initially involve massive construction projects and transfer of the human population.This change in local environment creates a major disturbance of the ecology and distribution of the rodents in this area.For the Shanghai EXPO site,we found that the density of rodents has steadily increased since its opening,indicating rapid and successful invasion by rodents (78.3%of Mus musculus,17.4%of Rattus flavipectus and 4.3%of Rattus norvegicus) .