OBJECTIVE To characterize the olfactory dysfunction in 50 Parkinson's disease (PD) patients with the University of Pennsylvania 12 smell identification test (UPSIT), establishing a comparison with 76 age-matched healthy controls, and associate with clinical and epidemiologic picture. METHODS The PD group was evaluated in phase "on" through United Parkinson's disease rating scale, UPSIT, and Hoehn and Yahr stage and the control group with the UPSIT. RESULTS The mean UPSIT score was 5.7 in PD patients and 9 in the control group. Patients that presented initially resting tremor and those that currently have tremor, rigidity and bradykinesia had a significant lower scores. There were negative correlation between patients' age and PD stage with the UPSIT scores. There were no correlation between olfactory scores, age at the initial PD symptoms and disease duration. CONCLUSIONS Among PD patients 80% had olfactory deficit and, therefore, smell evaluation may be a tool to make PD differential diagnosis.