Tomato [(Solanum lycopersicum Mill.) Wetted] is one of the most important vegetable crops grown in India. However, modern cultivars of tomato have a limited genetic diversity further the demand for high yielding disease resistant hybrids is alarming. In this study an effort was made to increase genetic variability for development of ToLCV resistant high yielding varieties and hybrids by utilizing exotic tomato breeding lines. Diversity analysis of 19 exotic tomato breeding lines and popular varieties viz., Pusa Ruby (P20), Vaibhav (P21) and Arka-Vikas (P22) was made with the D2 analysis, PCA, RAPD and SRAP markers, which revealed that exotic lines are diverse from popular varieties. Nineteen exotic tomato breeding lines and cultivars viz., P20, P21 and P22 were crossed in line x tester design to assess the combining ability and heterosis. A perusal of the results indicated that P21 x PT4227A, P22 x CLN2123E, P21 x CLN2768A, P21 x CLN2777F, P21 x CLN2400B, P22 x CLN2460E, P22 x CLN2777B, P20 x CLN2498E and P20 x CLN2777F showed significant heterosis over the best check hybrid. Further these hybrids could be used to develop mapping population and breeding for hybrid development.