A series of test flights was conducted by the U. S. Navy over a 3-year period to evaluate the effects of icing on the operation of the ZFG-2 airship. In supercooled clouds, ice formed only on the forward edges of small protuberances and wires and presented no serious hazard to operation. Ice secretions of the glaze type which occurred in conditions described as freezing drizzle adversely affected various components to a somewhat greater extent. The results indicated a need for protection of certain components such as antennas, propellers, ad certain parts of the control system.