A method is described which allows for histochemical processing of thick (50-200 microm) and consecutive sections of neural tissue, a prerequisite for many neuroanatomical studies. Two examples are given: (A) biotin-dextran-amine (BDA) tracing of neuronal connections in 50-100 microm thick vibratome sections of the adult rat brain and (B) immunohistochemical analysis of tyrosine hydroxylase-positive bulbospinal fibers in 50 microm thick cryosections of spinal cord.