In cats where injections of HRP have been made in the cerebellar cortex, pontocerebellar fibers are visualized throughout their length. Likewise, injections of HRP into the pontine nuclei visualize the pontocerebellar fibers and these anterogradely stained axons can in fortunate sections be followed into the granular layer. A visualization of retrogradely filled pontocerebellar fibers was unexpected and its another example of the sensitivity of the Mesulam8 technique.