Objectives– An earlier study in l-dopa responding patients with idiopathic Parkinson's disease documented that progressive nigro-striatal degeneration shown with single photon emission computed tomography (SPECT) and the cocain analog iodine-123-beta-CIT (beta-CIT) correlated linearly with increasing motor scores in the Unified Parkinson's Disease Rating Scale (UPDRS). Here we have extended the study to include 2 tremor patients with mild parkinsonism, 2 poor l-dopa responders with parkisonism and 2 non l-dopa responders with severe parkinsonism. Methods– SPECT scanning was performed 20 h after injection of beta-CIT and UPDRS was done at the time of beta-CIT injection. Results– All patients in the present study showed less nigro-striatal degeneration in relation to UPDRS motor scores than the patients with idiopathic Parkinson's disease. Conclusion– The results suggest that the the combination of beta-CIT-SPECT and UPDRS motor scores has the potential to differentiate idiopathic Parkinson's disease from other parkinsonian conditions.