A simple method for preparing multitissue control blocks (MTCB) for im
munohistochemistry is described. Parallel rectangular tissue sections
are embedded in paraffin and sections cut from these blocks are mounte
d at one end of the glass slide. A section from the tissue to be stain
ed is mounted at the other end of the same glass slide. The slide cont
aining both the control and test sections is processed for immunohisto
chemistry, allowing both the tissue sample and the controls to be trea
ted equally in all steps. The control blocks can be tailored to includ
e different tissues or tissues fixed in different fixatives, according
to the needs of the laboratory. In contrast to MTCBs that contain lar
ge numbers of sections, ours provides adequate tissue for each positiv
e control and at the same time allows improved accuracy and diagnostic
sensitivity. MTCBs can be used as general control blocks for the majo
rity of routine immunohistochemical stains and for initial antibody sc
reening.