This study presents both numerical and experimental results regarding the effects of pollution on the flashover performance of glass suspension-type insulators. The finite element method (FEM) was used for simulating polluted insulators both at power frequency and at lightning impulse voltages. Partially conductive epoxy resin with graphite powder was used for modeling pollution on the insulators, which enabled the measurement of the electrical potentials on the polluted insulators. Numerical studies demonstrated the variations in the field distributions caused by the location and severity of the pollution as well as by the type of voltage applied. The simulations, which were verified to a degree through measurement, showed that pollution conductivities greater than 10(-6) S/m and 10(-3) S/m alter field distributions for power frequency and lightning impulse voltages, respectively. Unlike the results obtained for partially polluted insulators, the voltage distribution was almost linear for fully polluted insulators. Experimental studies revealed that the location of the partial pollution plays an important role in flashover performance for lightning impulse voltages but has a negligible effect for power frequency voltages.