Abstract Background: Studies have shown an association between electromagnetic fields and childhood leukaemia. The aim of this study was to determine whether there is an increased risk of lymphoproliferative disorders (LPD) or myeloproliferative disorders (MPD) associated with residence ≤300 m from high-voltage power lines. Methods: Case–control study of 854 patients diagnosed with LPD or MPD (including leukaemia, lymphoma and related conditions) aged 0–94 years comprising all cases diagnosed in Tasmania between 1972 and 1980. Controls were individually matched for sex and approximate age at the time of diagnosis. Results: Compared with those who had always lived >300 m from a power line, those who had ever lived within 50 m had an odds ratio (OR) of 2.06 (95% confidence interval 0.87–4.91) for developing LPD or MPD (based on 768 adult case–control pairs); those who had lived between 50 and 300 m had an OR of 1.30 (0.88–1.91). Adults who had lived within 300 m of a power line during the first 15 years of life had a threefold increase in risk (OR 3.23; 1.26–8.29); those who had lived within the same distance aged 0–5 years had a fivefold increase in risk (OR 4.74; 0.98–22.9). These associations were strengthened when analyses were repeated for 201 pairs with entirely Tasmanian residential histories. Conclusion: Although recognizing that this study has limitations, the results raise the possibility that prolonged residence close to high-voltage power lines, especially early in life, may increase the risk of the development of MPD and LPD later.