Introduction: Tofu wastewater is one of the results from the tofu making process. The isoflavone in tofu has poten- tial in the health sector as a nutraceutical. Oral nutraceutical delivery requires safety considerations of the digestive tract, one of which is the gastric organ. Method: This study uses true experimental in vivo. Samples were Wistar rat, divided into 6 groups: control group (K), dose 1 (6ml/kgW; D1), dose 2 (12 ml/kgW; D2), dose 3 (18 ml/kgW; D3), satellite dose 1 (6ml/kg ; S1) and satellite dose 3 (18 ml/kgW; S3). Tofu wastewater was given for 28 days plus 14 days without treatment for the satellite group. The number of neutrophil cells in the lamina propria and gastric mucosal damage were observed using a digital microscope with 100x and 400x magnification. Result: One-way ANOVA showed that there were no differences in the number of neutrophil cells between different groups (p>0.05). Kruskal-Wallis showed significant differences in rat gastric mucosal damage (p<0.05). Mann-Whitney showed signif- icant differences in the control group with the dose 2, dose 3, satellite dose 1 and 3 groups, likewise the comparison between the dose 1 with the dose 2 and 3 groups. Conclusion: Tofu wastewater does not give a difference in the number of neutrophil cells in lamina propria, but it gives toxic effects of gastric damage and does not show improve- ment to the destruction.