Dopamine active transporter (DAT) single photon emission computerised tomography (SPECT) is considered a useful and practical technique for early diagnosis of Parkinson's disease (PD) and assessment of its progression. The application of this technique, particularly as a surrogate marker for therapeutic and neuroprotective trials in Parkinsonism, however, is dependent on pathological validation. In the absence of human studies, we used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) primate models of Parkinsonism to verify correlation between the SPECT, immunohistochemical and behavioural data. The DAT SPECT data correlated strongly and significantly with the substantia nigra pars compacta tyrosine hydroxylase and Nissl cell counts as well as the behavioural scores. Within the limitations of small numbers inherent to such studies, this data provides the first attempt at pathological validation of SPECT in primates.