Capillary pressure microinjection is a popular method for the delivery of samples into cells. Needs for automatic reliable microinjection systems are growing, but the current systems do not possess ideal characteristics and many researchers do not even recognize the limits of the current systems. In many cases for example, the experiments are influenced by so called influx or efflux. This paper discusses the limits and challenges related to the automatic microinjection of single adherent cells. The discussion focuses on the reasons for the variability of the injected volume and shows the complexity of the problem. Solutions are outlined and future steps sketched. Future developments in the field of microinjection are proposed.