Tanzania Journal of Agricultural Sciences 2015, Vol. 13(1) :67-73Tomato (Solanum lycopersicum L.) is an important food and income generating crop among small holder farmers in Tabora Region. High yield is a major ambition to tomato plant breeders and farmers. The purpose of the study was to determine the influence of environmental conditions in Tabora Region on the growth and yield of newly introduced tomato varieties. The tested varieties were Duluti (LBR6), Meru (LBR 50 - 2) and Kiboko collected from AVRDC Arusha, Tanzania. The experiment was conducted both in the screen house to see the performance of the varieties under the controlled environment and the field at Tumbi Agricultural Research Institute. A screen house experiment was laid out in a Completely Randomized Design (CRD) while Randomized Complete Block Design (RCBD) was used in the field both had three replications. Yield, vegetative and reproductive data were collected and subjected to analysis of variance using the GENSTAT programme. Yield and yielding components varied among tomato varieties in both experiments. The variety, Meru, with 92 ton/ha was significantly (p<0.001) higher than Duluti and Kiboko with 74 and 69 ton/ha respectively under field conditions. The forty tone/ha observed from Duluti was significant (p<0.05) higher than the 32 ton/ha harvested from each of the other varieties. Variation in yield and yielding components among tomato varieties in both experiments may be attributed to genetic and environmental differences. Regardless, of such variations both varieties showed better production in Tabora. Their good performance was attributed largely to their apparent better adaptation, which enabled them to grow more vigorously. They will therefore be suggested for adoption by Tabora growers.