Monosodium glutamate (MSG) is a flavour enhancer often added to restaurant foods, canned vegetables, soups, deli meats and other foods. The toxic effects of monosodium glutamate on the male reproductive system have been recognized. This study aimed to investigate the impact of in utero exposure to a high-dose of MSG on the testicular morphometry and physical findings of Wistar rat offspring exposed intra-uterine. Forty (40) adult pregnant Wistar rats (150–200 g) were randomly selected and divided into four groups. Group 1 (control) received distilled water, while groups 2, 3 and 4 received 1 g/kg, 2 g/kg, 4 g/kg as 1 mL body weight of MSG orally throughout pregnancy respectively. The pups were examined at delivery and allowed to grow for 4 weeks. The animals were sacrificed on the 28th day after delivery. The testes were harvested and weighed. Histomorphometric analysis of the testis were carried out and the morphometric parameters: diameter of seminiferous tubules, cross-sectional area (A) of seminiferous tubules, germinal epithelium thickness, the numerical density, seminiferous tubule numerical density and seminiferous volume were measured using photomicrograph and image J software. Data were analysed using ANOVA at α 0.05. The MSG-treated groups compared to the control group had higher body weights and alteration in the morphology of the testicular tissue. There was also a decrease in the diameter of the seminiferous tubule of the testis with an increasing dose of MSG, a dose-dependent decrease in the cross-sectional area of seminiferous tubules and the thickness of the testis germinal epithelia of the testis. Maternal exposure to high doses of monosodium glutamate adversely affected testicular morphometry and exacerbated testicular tissue alterations.