The effects of seed priming and ageing treatments on the performance of tomato seeds were studied according to a number of indices of seed vigour in the faculty of agriculture at Ferdowsi University with Yekan Seed Company. Four cultivars of tomato seeds (Falat CH, Falat Karoon, Calj-N3 and Early Urbana Y) were primed in distilled water (hydropriming) for 12 hours, (KNO3+K2HPO4),PEG8000 and urea aerated solutions for 5 days at osmotic potential of -1.25 MPa or aged at 13% seed moisture content at 50 °C for 6 days. After the selection of (KNO3+K2HPO4) as the best priming treatment by comparing germination and emergence factors, seeds of this superior priming treatment were compared to the control and aged seeds according to some other vigour tests such as weight comparison, conductivity and tetrazolium tests. Falat Karoon had the lowest vigour among other cultivars. The tetrazolium test, revealed that the embryo of primed seeds were much more distinct and clearly distinguishable from the surrounding endosperm than those of control or aged seeds in all cultivars. It seems that (KNO3+K2HPO4) could be  considered as the superior priming treatment. It seems that mean germination time- (MGT) and mean emergence time-(MET) are more suitable factors than final germination and emergence percentages, to evaluate tomato seed vigour. It seems that weight comparison and conductivity tests are unreliable as vigour tests for tomato seeds. However, tetrazolium test with more research can be suitabe as a vigour test for tomato seeds.