In Reply: Our study showed that cell phone activation was associated with metabolic increases in brain regions closest to the antenna and that the increases showed a negative linear correlation with distance from the antenna. In their letter, Dr Kosowsky and colleagues point out that realistic RF-EMF models are likely more complex than the model we used. The assumptions about the model are only relevant in interpreting the spatial distribution of the observed effect, but they have no impact on the significance of the effect itself. Furthermore, the narrow range of distances to the antenna in our study (9-11 cm) suggests that a first-order Taylor approximation for any potential RF-EMF model might be sufficiently accurate. The observed linear decrease in the metabolic effect with distance is consistent with this.