Methods provided by nuclear medicine may be helpful in diagnosis of Parkinson's disease (PD). For that purpose, the sensitivity of iodine-123 metaiodobenzylguanidine ([123I]MIBG) scintigraphy and [123I]FP-CIT single photon emission computed tomography (SPECT) was studied in patients with PD onset (Hoehn and Yahr Stage 1). Cerebral [123I]FP-CIT and cardiac [123I]MIBG scintigraphy were carried out in 18 patients with idiopathic Parkinson's disease, according to Hoehn and Yahr Stage 1. For quantification purposes, we calculated the striatum/posterior lobe binding of FP-CIT and the heart-to-mediastinum (H/M) count ratio regarding MIBG scintigraphy. In 15 of 18 patients, we observed markedly reduced or asymmetric striatal FP-CIT tracer accumulation. FP-CIT binding of the affected striatum was significantly lower as compared with that of the unaffected side. Striatal FP-CIT binding correlated significantly with the motor part of the Unified Parkinson's disease rating scale (UPDRS) but not with age, disease duration, or gender. MIBG scintigraphy delivered significant pathological results in 13 of 18 patients. There was no significant correlation between the H/M ratio relating to MIBG scintigraphy and the motor part of UPDRS, age, disease duration, or gender; however, binding of striatal FP-CIT correlated significantly with cardiac MIBG accumulation. According to the clinical criteria, it might be difficult to prove the diagnosis of PD in patients with slight symptoms and in these cases, FP-CIT SPECT and MIBG scintigraphy may contribute to the early diagnosis of PD. In addition, the functional loss of nigrostriatal and cardiac sympathetic neurons seems to be coupled closely.