Twenty-three precommercial field corn lines (Zea mays) were screened in the greenhouse and in vitro for the ability to support reproduction of Heterodera zeae. Although H. zeae reproduced on all corn lines, reproduction was only 0.4 to 4.5% on the five least suitable corn lines in greenhouse tests compared with the susceptible check line Pioneer brand 3184. The least suitable experimental line supported an average of 30 cysts plus females after 8 weeks growth, whereas the susceptible check, Pioneer brand 3184, averaged 8,183 cysts plus females per pot. Reproduction of H. zeae in in vitro root cultures of the 23 lines and susceptible check cultivar, Iochief, was too low to be of any value in detecting resistance to this nematode under the conditions of these tests. Key words: corn cyst nematode, corn, greenhouse, Heterodera zeae, in vitro, nematode, reproduction, resistance, Zea mays.