Tomato fruit firmness is crucial for reducing loss during handling and marketing. The current study was conducted to identify the type gene action, heritability and genetic gain from selection of tomato fruits in addition to its associations with other traits .The bi-parent cross 'Peto-86' (high fruit firmness) x 'Supermarmande' (low fruit firmness) was used. The investigation employed the analysis of generation (two parents, F1, F2 and F3) mean and variance components based on the five parameters model. It was observed that all gene effects were influential (d= Additive effect, h= dominance effect, l= Dominance x Dominance and i= Additive x Additive). Effect of d, h and i had positive sign while l value was large and negative. Heritability estimate in narrow sense for F2 was 28.0% and elevated to 40.5% in F3. Genetic gain from selection was 11.19% relative to F2 mean. Associations for fruit firmness with other main yield and fruit quality traits were few in number and low in magnitude. It was concluded that improvement of the fruit firmness can be achieved through direct selection in later generations.