The trace element composition of individual fluid inclusions was investigated by using synchrotron radiation X-ray fluorescence for analysis and Monte Carlo simulations for quantification. To validate the input parameters of the Monte Carlo simulation code for the applied spectrometer, area scan measurements on synthetic standard reference glasses (NIST 612 and NIST 610) were performed. Results yielded an accuracy of generally better than 20% for all elements with Z between 37 and 92 at a standard deviation of less than 7%. The analytical procedure was then applied to synthetic inclusions in quartz: single point analysis yielded an accuracy between 10 and 30 % with a reproducibility of ± 20 % and a repeatability of ± 7 % for the elements Cu, Rb, Sn and Cs. Ten trace elements (Mn, Fe, Cu, Zn, As, Rb, Nb, Sn, Sb, Cs) with concentrations between 2 and 10500 ppm were determined in fluid inclusions of hydrothermal quartz hosts from the Ehrenfriedersdorf Complex, Germany. Inclusions of three evolutionary stages of the Ehrenfriedersdorf Complex were studied. Vapour-rich inclusions of the pegmatite stage have low concentrations of all elements with Z > 20. Inclusions of the hydrothermal stage record progressive enrichment and differentiation in trace elements. Fluids of the early hydrothermal stage are enriched in Sn, Cu and As. Subsequently, they evolve to Fe-, Mn-, Zn- and Cs-rich fluids.