Fifteen patients with primary lung cancer or pulmonary metastases were treated with electrostatic therapy (EST). The patients were treated with either low voltage (200 to 1200 V), high voltage (500 to 2500 V), or high voltage together with high magnetic field. At six months after EST, tumour regression was observed in two cases, relief of symptoms, but no change in tumour size, in five cases, and no effect of EST in nine patients. In conclusion, no marked effect of EST for treatment of cancer could be observed.