OBJECTIVE: Liver transplantation is the only potentially curative treatment for familial amyloidotic polyneuropathy (FAP). We investigated cardiac autonomic function in 63 transplanted Swedish FAP patients. METHODS: Heart rate variability (HRV) was recorded between 1-17 (mean 8) months before, and 10-40 (mean 20) months after transplantation. HRV was analysed by power spectrum analysis, but only in patients without arrhythmia (n=38). RESULTS: Patients with moderate cardiac autonomic dysfunction showed a statistically significant reduction in HRV after transplantation, as compared to the pre-transplant recording. Patients with severe cardiac autonomic dysfunction presented unchanged HRV after liver transplantation. Twenty patients were excluded because they presented cardiac arrhythmia, five of these presented increased HRV after transplantation but had developed subtle arrhythmias, thus, they had not improved cardiac autonomic control. Five patients were excluded because they were pacemaker-treated. CONCLUSIONS: The reason why HRV decreased after transplantation remains unclear, but there are several possibilities: 1) liver transplantation did not stop the deterioration in cardiac autonomic function; 2) the deterioration continued until transplantation and was then halted; or 3) a sudden reduction in HRV occurred in connection with the transplantation procedure. Nonetheless, this study failed to disclose any improvement in cardiac autonomic function after liver transplantation for FAP.