Trembesi (Samanea saman (Jacq.) Merr.) leaves contain various secondary metabolites, including flavonoids, alkaloids, saponins, tannins, phenolic compounds, and terpenoids, which are known to possess diverse biological activities. However, information regarding the safety profile of the 70% ethanol extract of S. saman leaves remains limited. Therefore, a preliminary toxicity evaluation is necessary. This study aimed to determine the toxicity profile of the 70% ethanol extract of S. saman leaves based on the LC₅₀ value using Artemia salina Leach larvae. This laboratory experimental study employed the Brine Shrimp Lethality Test (BSLT) with a post-test only control group design. The extract was prepared by maceration using 70% ethanol and tested at concentrations of 10, 100, 500, 1,000, and 5,000 ppm. Larval mortality was observed after 24 hours of exposure, and the data were analyzed using probit analysis to determine the LC₅₀ value. The results showed that larval mortality increased with increasing extract concentration, reaching 18.92%, 52.78%, 79.55%, 91.23%, and 97.22%, respectively. Probit analysis indicated an LC₅₀ value of approximately 72.66 mg/L, classifying the extract as toxic according to the toxicity classification proposed by Haryanto et al. (2023). These findings indicate that the 70% ethanol extract of S. saman leaves exhibits significant toxicity toward Artemia salina Leach larvae and may contain bioactive compounds with potential pharmacological applications. Further toxicity and pharmacological studies are recommended to evaluate its safety and therapeutic potential and is useful as a natural pesticide.