The Drammen Granite is a subvolcanic complex, intruded during the Permian igneous activity in the Oslo Paleorift. Molybdenite deposits occur within the complex in large discrete quartz veins, accompanied by moderate alteration of the granite. Microchemical and Sr-isotopic studies of fluids trapped in quartz from miarolytic cavities allow characterization of fluids in the granite. The results compare well with compositions interpreted from microthermometry studies. The observed range in K/Na, Ca/Na and the calculated concentrations of metals in the original fluids suggest that different stages of development are represented. Some of the fluids probably represent early magmatic stages. K/Rb results and the average Sr-isotope composition indicate equilibrium between the fluids and the granite magma.