BACKGROUND: The aim of this study was to evaluate the cardiac sympathetic nervous system function in haemodialysed(HD), non-diabetic patients by iodine-123 meta-iodo-benzylguanidine(123I-mIBG). MATERIALS AND METHODS: Planar scintigraphy of the chest was performed in 36 HD, male patients; 15 minutes and 4 hours post injection of 370 MBq of 123I-mIBG. The semi quantitative analysis of myocardial tracer uptake was expressed as routine heart to mediastinum (H/M) ratio: 15 minutes (early H/M) and 4 hour (late H/M) post administration as well as washout of the tracer from myocardium (WR). 24-hour Holter studies were recorded and heart rate variability (HRV) was evaluated. Patients were divided into two groups according to the H/M value: group A patients with H/M > 1.8 which has been accepted as a norm,and group B patients with H/M < 1.8. RESULTS: In 21/36 patients H/M ratio was below normal values.Significant differences between groups A and B were found among the following parameters: early H/M and late H/M ratios,WR and duration of haemodialysis therapy. CONCLUSIONS: In patients with abnormal function of cardiac sympathetic nervous system, expressed by means of H/M ratio below 1.8, duration of haemodialysis treatment was longer.Duration of HD appears to be an important factor influencing cardiac sympathetic nervous system.