We have studied the electrical properties of two series of ferromagnetic SrRuO3 thin films: (a) films grown at different substrate temperatures; (b) after irradiation of a metallic SrRuO3 sample with progressive doses of He+ ion irradiation. In both cases, an evolution from metallic to insulating behaviour is observed, suggesting a metal–insulator transition. Damage by ion implantation produces a significant decrease of the Curie temperature, whilst in the first series of samples no significant change in Tc (∼160K) takes place.