Studies on the evaluation of the impact of the release of the tomato plants with introduced gene of TMV resistance on the environment were carried out from January, 1989, to January, 1992, mainly at the National Institute of Agro-Environmental Sciences (NIAES) in collaboration with the National Institute of Agrobiological Resources (NIAR) and the National Agriculture Research Center (NARC). Experiments were carried out according to the guidelines enacted by the Science and Technology Agency and the Ministry of Agriculture, Forestry and Fisheries. The following characteristics were compared between the original plants and transgenic plants: (1) growth characteristics such as plant height and vigor, (2) pollen dispersion based on fruit set on emasculated flowers, (3) kinds of chemical substances produced by plants such as allelochemicals in plant tissues, soil and air, (4) microorganism flora in soil, (5) overwintering ability, (6) ability to become a weed, (7) the amount of Agrobacterium on plants, and (8) kinds of flower-visiting-insects. Cultivation was safely carried out. Since no harmful impact on the environment where the transgenic tomato plants had been cultivated was detected, it is suggested that this tomato strain can be cultivated in an open field. The TMV resistance was maintained throughout generations. These transgenic tomato plants were cultivated in an ordinary field in the summer of 1992 in the campus of the NIAEA.