The current research was conducted to determine the effects of different potassium (K) and iron (Fe) rates on the growth and some macro nutrient uptake of maize. For this purpose, five K (1, 2, 4, 6 and 8 mM) and four Fe (30, 60, 90 and 120 mu M) doses were applied to maize (Zea Mays L. cv. BSC 6661) plants in a re-circulated hydroponic system. Increasing K and Fe levels had positive effects on dry weight of the maize leaves and roots. The total Fe and active Fe concentrations and their uptake increased with the increasing levels of Fe and K, but these amounts decreased with the highest K dose. The addition of increasing levels of K decreased the P, Mg, and Ca concentrations in both leaves and roots of maize. Although the lowest dose of K and Fe has positive effects, the elevated K and Fe doses decreased their uptake in both roots and leaves.