The 3.8 MeV proton beam from the University of Florida Van de Graaff accelerator has been used to perform trace element analysis of approximately 1200 samples (mostly from autopsies) of human tissues by proton-induced X-ray emission analysis (PIXE). Fifteen different organs and a variety of diseases have been studied. Preliminary data are presented indicating the variations of various elements in human kidney as a function of age. Analysis of samples from infants also indicate essential and non-essential elements in human kidney. On the average twelve trace elements (with atomic number equal to or larger than nineteen) are observed in each organ. Quantitative measurements have been made on several elements including K, Ca, Mn, Fe, Cu, Zn, Pb, Br, Rb, Sr, Cd, and Ba.