Both labial salivary gland and gingival biopsies were taken from 19 patients with clinical findings suggestive of secondary amyloidosis. Amyloid deposits were present in all salivary gland biopsies (19/19) while amyloid deposits in gingiva were observed only in three cases (16%). No amyloid was found in similar biopsies from 11 control patients. Periductal amyloid involvement was found along the basement membrane in all salivary gland samples; additionally, 16 cases had periacinar infiltration (84%), 13 had perivascular (68%) and 7 (37%) showed interstitial deposits. Amyloid in gingiva was seen along the epithelial basement membrane, as in salivary glands, although in isolated areas and scattered at the top of some dermal papillae and small blood vessels. In secondary amyloidosis it therefore appears that amyloid is deposited along the epithelial basement membrane before perivascular deposition occurs. This study presents a new highly sensitive and reliable method for the diagnosis of secondary amyloidosis, a method which is technically simple, free from complications and well-accepted by the patients.