Diagnosis of amyloidosis still relies on tissue biopsy for microscopic examination. Biopsy from a symptom-giving organ may be used but more often an easily available tissue which is affected in most forms of systemic amyloidosis is utilized. Rectal biopsy has its place but a fine needle aspiration biopsy of subcutaneous adipose tissue offers a safe and more convenient alternative. With increasing knowledge about the chemical nature, prognosis and treatment of the different systemic amyloidoses there is an increasing demand of exact chemical typing of amyloid deposits. This typing can be performed immunologically on tissue biopsies, e.g. from subcutaneous adipose tissue, by several different methods. The distribution of amyloid in the body and the therapeutic effects can be monitored by scintigraphy after administration of radiolabelled amyloid P-component.