Compared to spherical particles, inhaled fibers may cause enhanced adverse health effects because of their specific shape, thus acting as so-called physical carcinogens. The chemical composition of fibers plays a determining role on the durability and hence may play a potential role in related health effects due to their toxic components. The physical properties, that is, length, diameter, and size distribution, and the chemical composition of fiberglass materials sampled at a Hungarian glass wool factory were investigated. The morphology of the particles was studied by optical microscopy and scanning electron microscopy (SEM), while for the chemical analysis instrumental neutron activation analysis (INAA) and SEM combined with energy-dispersive x-ray analysis (EDX) were used. Deposition fractions of the fibers in different regions of the lung and in the whole human respiratory system were computed by a stochastic lung deposition model for different flow rates and equivalent diameters, using experimentally determined size distributions.