This study investigates whether chitosan, a biopolymer derived from chitin, contributes to the formation of calcium oxalate (CaOx) kidney stones. Chitosan is widely used in biomedical applications due to its biocompatibility and pharmacological properties. However, its renal accumulation and effect on calcium excretion raise concerns about its potential role in kidney stone formation. The study evaluated the antioxidant capacity of chitosan and its impact on CaOx crystal formation in vitro. Chitosan was confirmed to have a characteristic structure through FTIR and 1H NMR analyses. It showed low or no antioxidant activity in several tests, but exhibited strong copper-chelating activity. In vitro, chitosan primarily induced the formation of monohydrate CaOx crystals, which are more prevalent in patients with urolithiasis. Chitosan also altered the morphology and size of these crystals and changed their surface charge, making them more positively charged, which could facilitate their interaction with renal cells. The study found that chitosan significantly increased the formation of CaOx crystals, particularly monohydrate crystals. It also increased the positive surface charge of these crystals, potentially enhancing their ability to interact with renal cells and contribute to kidney stone formation. While the study suggests that chitosan may induce CaOx crystal formation, further in vivo studies are needed to confirm these findings and assess the risk of using chitosan. The results indicate that chitosan may play a role in the development of kidney stones, although its exact mechanism and long-term effects require further investigation.This study investigates whether chitosan, a biopolymer derived from chitin, contributes to the formation of calcium oxalate (CaOx) kidney stones. Chitosan is widely used in biomedical applications due to its biocompatibility and pharmacological properties. However, its renal accumulation and effect on calcium excretion raise concerns about its potential role in kidney stone formation. The study evaluated the antioxidant capacity of chitosan and its impact on CaOx crystal formation in vitro. Chitosan was confirmed to have a characteristic structure through FTIR and 1H NMR analyses. It showed low or no antioxidant activity in several tests, but exhibited strong copper-chelating activity. In vitro, chitosan primarily induced the formation of monohydrate CaOx crystals, which are more prevalent in patients with urolithiasis. Chitosan also altered the morphology and size of these crystals and changed their surface charge, making them more positively charged, which could facilitate their interaction with renal cells. The study found that chitosan significantly increased the formation of CaOx crystals, particularly monohydrate crystals. It also increased the positive surface charge of these crystals, potentially enhancing their ability to interact with renal cells and contribute to kidney stone formation. While the study suggests that chitosan may induce CaOx crystal formation, further in vivo studies are needed to confirm these findings and assess the risk of using chitosan. The results indicate that chitosan may play a role in the development of kidney stones, although its exact mechanism and long-term effects require further investigation.