The leakage current on post and rod insulators without sheds was measured. The porcelain and silicone rubber insulators were tested at Glogow station under the voltage of 75 kV The current on porcelain insulators are greater than the current on silicone insulators probably during the rain. However, in very humid air the currents on both insulator types are similar. The silicone rubber insulators are about two times more contaminated than the porcelain insulators.