Background: Many developing nations face a severe public health problem due to parasitic schistosomiasis. Aim: This study evaluates the use of grape seed extract with PZQ against Schistosoma mansoni in vivo. Materials & Methods: In this study, forty-eight male albino mice infected with S. mansoni were given grape seed extract (100 milligram/kilogram B.W., once daily for 10 days) and PZQ (250 mg/kg B.W.) orally, six weeks after infection. Parasitological aspects, antioxidant activity, and immunological parameters were determined following treatment. Results: The total worm burden and ova count/g in hepatic and intestinal tissue decreased after administration of PZQ or combined with grape seed extract. Concurrently, the number of dead eggs increased significantly. Serum AST and ALT activities were diminished after being exposed to grape seed extract. Increases in the antioxidant hepatic enzyme activities of catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST) were observed in infected mice treated with grape seed extract, PZQ or a combination of both. The levels of vascular adhesion molecules-1 (VCAM-1) and tumour necrosis factor-alpha (TNF-α) were significantly lower in the grape seed extract and PZQ group compared to the S. mansoni infected group. Conclusion: Most of the effects observed when grape seed extract and PZQ are used together indicated that PZQ and grape seed extract work together to fight parasites, prevent fibrosis, and change the host's immune responses.