Quantitative analysis of confocal imaging experiments require more stringent quality control of instrument function than qualitative imaging. Unfortunately, there are no standard procedures for quality control that are uniformly implemented, and, in multi user facilities experimenters rarely have access to the QC information. This paper proposes an easy and very efficient protocol that could be performed at the beginning of each day, experiment or even slide. It takes only a few minutes to assess laser stability, stage stability, channel registration in 3 dimensions and flatness of field. The information may be used either to calibrate data or, in more severe cases to request servicing the instrument.