Double immunoenzymatic labeling of 2 different molecules in tissue sections is a widely used technique. However, it is time consuming since the 2 immunoenzymatic procedures are carried out in sequence, and they must also be optimally performed to avoid unwanted background labeling. In this paper, we report that double immunoenzymatic staining performed using automated immunostaining apparatus considerably reduces the requirements in terms of time and is also highly reproducible and free of background. Three tissue markers can also be visualized by performing (after immunoperoxidase labeling) 2 sequential immuno-alkaline phosphatase procedures using different substrates. Furthermore, single or double detection of mRNA by in situ hybridization can be combined with immunoenzymatic labeling. Finally, automated labeling could also be performed on peripheral blood and bone marrow smears, opening the possibility of using this procedure in the analysis of hematologic/cytology samples.