Although many publications have demonstrated the potential of PIXE for biologicl trace element analysis few as yet report its large-scale application as a diagnostic aid in medicine or as a basic tool in biological or biochemical research. To emphasise PIXE's unique capability in these areas ,we present a detailed comparison of normal trace levels in serum and tissues with PIXE's actual performance to date. Some medical projects currently employing PIXE are reviewed and further possible applications examined.