Estimation of diversity among maize inbred lines would determine breeding strategies, classify inbred lines, define heterotic groups and predict future hybrid performance. The objective of this study were to estimate the phenotypic and genetic diversity of 15 inbred lines developed in the Institute of Crop Science "Porumbeni" and which were classified into the Iodent heterotic group. The researches were aimed to: i). evaluation of the important morphobiological characters of inbred lines ii). estimation of phenotypic distance between related and unrelated lines, iii). evaluation of heterosis in crosses with related and unrelated lines, iv). assessment of the inbred lines diversity at the non-additive gene interactions level and v). assessing the breeding value of inbred lines. In the most of cases (84%), between inbred lines was observed a high or medium degree of phenotypic similarity. The degree of heterosis in related hybrids ranged from -12.2 to 83.9%, but have been lower, than in the hybrid combinations between unrelated lines (h = 51,2 - 134,5%). The genetic differences at the nonadditive interactions level have been reveled between parental lines of the15 hybrids, in other cases (84%) non-additive genes effects were negative or insignificant, determining a high degree of relatedness between parental components. The results show that the studied lines are some new creations, more or less differentiated phenotypically and genotypically from each other, but these lines are part of the Iodent heterotic group