A totally randomised design employing four treatments (20,000, 25,000, 33,333 and 50,000 plants∙ha-1 population density) and three repetitions was used for ascertaining optimum population density and obtaining the highest yield in tomato crops grown in the middle Sinu valley. Direct measurements taken included: plant height, number of leaves, leaf area, fruit number and yield. Growth indexes were also calculated: crop growth rate (CGR), net assimilation rate (NAR), relative growth rate (RGR), leaf area index (LAI) and leaf area duration (LAD). The 50,000 plants∙ha-1 population obtained the highest plant height (240.33 cm average after 120 days following being transplanted), highest leaf number (196.7 at 120 days), highest leaf area (8,109.73 cm2 at 105 days) and highest fruit yield per plant (1,699.27 g). The same treatment (50,000 plants∙ha-1) presented the highest CGR (40.88 g∙m-2∙day-1 after 105 days following being transplanted), NAR (0.00343 g∙cm2∙day-1 at 75 days), RGR (0.1532 g∙g-1∙day-1after 45 days), LAI (4.04824 at 105 days) and LAD (56.37075 days after 120 days following being transplanted) mean values.