The method of proton-induced X-ray emission (or PIXE) analysis has been investigated with reference to the study of minor
and trace elements in biological tissue. Methods of specimen preparation have been investigated, and optimum instrumental
conditions arrived at. The lower limits of detection for lead and zinc in blood have been investigated and have been found
to be approximately 0.3 and 0.1 ppm for lead and zinc respectively, for a proton energy of 2.5 MeV. The concentrations of
copper, zinc and iron have been studied in normal and diseased human liver tissue. In cirrhotic tissue the copper levels are
substantially raised. We note also a diminution in liver iron in a case of alcoholic cirrhosis associated with clinical anaemia;
and a blood zinc deficiency in primary biliary cirrhosis. The results are discussed in relation to existing work.