Deficient iodine intake may be associated with increased thyroid cancer incidence. We investigated whether iodine deficiency (ID) affects angiogenic processes in thyroid malignant cells by altering the ROS-HIF-VEGF pathway. Methods: Goiters were obtained in RET/PTC3 transgenic and wild type (wt) mice and ID was induced in three thyroid carcinoma cell lines (TPC-1, 8305c, R082-w1). Thyroid blood flow, VEGF mRNA and protein, and HIF-1 protein expression were measured. The role of HIF-1 and of reactive oxygen species (ROS) was assessed. Results: The goitrogen treatment increased the thyroid blood flow in wt and RET/PTC3 mice. Compared to wt mice, basal VEGF expression was higher in RET/PTC3 mice and increased with the goitrogen treatment. In the three cell lines, ID induced a marked increase in VEGF mRNA and a moderate increase in HIF-1 protein expression which were not transient as in normal cells. ID-induced VEGF mRNA expression was fully (8305c), partially (TPC-1), or not (R082-w1) blocked by echinomycin. NAC had no effect on ID-induced VEGF mRNA and HIF-1 protein expression in the three cell lines. Conclusions: These results suggest that, in contrast with normal cells, ID-induced angiogenesis in cancer cells occurs via alternative and likely less controlled routes, thereby leading to uncontrolled growth.