The present invention provides a method of producing an adenoviral vector stock by providing a culture of cells permissive for growth of adenoviral vectors, wherein the cells are in a medium, culturing the culture under conditions to permit growth of the cells, perfusing fresh medium trough the culture for a period of about 1-6 hours, in an amount of at least about two times the volume of medium in the culture, while the density of the cells in the medium is about 40-70 % of the density of cells obtained in the medium when the growth of the culture is in the stationary phase, contacting the culture with adenoviral vectors under conditions permissive for the infection of the cells, culturing the infected cells to replicate the adenoviral vectors, and harvesting the infected cells to obtain an adenoviral vector stock. A method of obtaining a synchronous culture of cells is also provided.