The Antarctic moss Sanionia uncinata (Hedw.) Loeske has shown high ultraviolet (UV)‑absorbers content after exposition to high levels of UV‑B radiation and can be an important source of antioxidants. Objective: The aim was to investigate photoprotection and mutagenicity by the aqueous extract (AE) and hydroethanolic extract (HE) from the Antarctic moss S. uncinata. Materials and Methods: Photoprotective activities were determined through survival curves of Escherichia coli strains, after UV irradiation in an aqueous solution of thymine and in vitro sun protection factor (SPF). The Salmonella/microsome assays were applied to assess the mutagenicity. Results: Both extracts induced photoprotection against UV‑C radiation. The AE showed a higher protection than the hydroethanolic one against UV‑induced thymine dimerization. The SPFs were low in both extracts. In association to benzophenone‑3 a significant increase in the SPF was detected for the AE, and a significant decrease was induced by the HE. No mutagenicity was found in the both extracts. Furthermore, it was observed absence of cytotoxicity. Conclusion: Water‑extractable compounds seem to contribute on photoprotection of this Antarctic moss.