Since oxidative stress has been implicated in amyloid diseases, a study of scavenger treatment of hereditary transthyretin amyloidosis was undertaken on 23 familial amyloidotic polyneuropathy (FAP) patients. Nine patients had undergone a liver transplantation for the disease. Twenty patients completed the 6-month study period of scavenger treatment (vitamin C, 1 g, three times daily, vitamin E, 0.1 g, three times daily and acetylcysteine, 0.2 g three times daily). They were evaluated clinically and by immunohistochemical measurement of hydroxynonenal (HNE), a product of lipid peroxidation, in biopsy specimens. For non-transplanted patients, no improvement was found for HNE in relation to the amyloid content in biopsy specimens, whereas a tendency to a decreased amount was noted for transplanted patients. Clinically, no differences were found for non-transplanted patients, but an increased nutritional status, measured by a modified body mass index (mBMI) was noted for transplanted patients. In summary, scavenger treatment with the drugs and doses used in the present study appears to be unable to decrease lipid peroxidation in amyloid-rich tissue in non-transplanted FAP patients. For transplanted patients, lipid peroxidation tended to decrease, and the nutritional status measured by mBMI improved, even though the findings may be explained by liver transplantation alone, scavenger treatment may facilitate recovery after transplantation.