This study was conducted to determine the effect of magnetized water on the vegetative growth and yield of tomato. The values of magnetic flux densities used for treating the irrigation water varied from 124 to 719 G (T2 to T10) were produced from electromagnet and T1 was the control experiment which was not treated with magnetic field. The water after passing through (treated with) magnetic field (T2 to T10) was called magnetized water while the control experiment (T1) was called non-magnetized water. The experimental layout for the study was a 10 by 10 Latin Square Design. The tomato (variety UC82B) was planted in 100 buckets in a transparent garden shed for 130 d and irrigated with magnetized and non-magnetized water, respectively. The heights of tomato plant for magnetized water (T2 to T10) after 68 d were 546, 565, 575, 572, 596, 561, 572, 558 and 572 mm and the total yield after 130 d were 1900.7, 1673.6, 2043.4, 1848.6, 1897.2, 1336.5, 1697.3, 1758.1 and 2004.4 g, respectively. The height of tomato plant and the yield for non-magnetized water (T1) were511 mm and1205.5 g, respectively. The results indicated that tomato irrigated with magnetized water grew faster than the non-magnetized water. The increment in yield with the magnetized water varied from 39% to 70% compared to that of non-magnetized water.