Objective:To examine whether an increased level of chromosome damage occurs in the stimulated lymphocytes of radio‐linemen after long‐term but intermittent exposure to radio‐frequency radiation (RFR) during the course of their work.Design and participants:Chromosome studies were performed on blood samples from 38 radio‐linemen matched by age with 38 controls, all of whom were employed by Telecom Australia. The radio‐linemen had all worked with RFR in the range 400 kHz‐20 GHz with exposures at or below the Australian occupational limits, and the controls were members of the clerical staff who had no exposure to RFR. Two hundred metaphases from each subject were studied and chromosome damage was scored by an observer who was blind to the status of the subjects.Results:The ratio of the rate of aberrant cells in the radio‐linemen group to that in the control group was 1.0 (95% confidence interval, 0.8–1.3). There were no statistically significant differences in the types of aberrations that were scored.Conclusion:Exposure to RFR at or below the described limits did not appear to cause any increase in chromosomal damage in circulating lymphocytes.