Development of inbread-based populations which are heterotic to each other was considered one of the primary goals when CIMMYT started of this study were to determine the combining ability and heterotica patters of tropical maize(Zea mays L.) inbred lines developed at CIMMYT and to identify and form beterotic grous for the topics. 92 tropical late white inbred lines at S3-S6 levels of inbreeding derived from nine CIMMYT populations and pools were crossed to four tester lines(two dent and two flint).259-270