Abstract: The invention is directed to a method for performing work on cells of a cell culture which includes microinjecting cells in the cell culture or drawing liquid from an individual cell or withdrawing whole cells with the aid of suction from the cell culture. The system is computer-supported and a marker movable in the image on a monitor is superposed on a television image of the cell culture. The marker is positioned in the television image on the cell to be injected by the operator by means of a relative movement of the marker with respect to the image. The coordinates of the cells marked in this way are stored by the computer which thereafter advances the capillary point automatically to the selected cells and penetrates the latter.