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Vibrio harveyi (Vh) CAIM 1792 strain was isolated from Litopenaeus vannamei affected with “Bright-red” Syndrome (BRS). The strain grew in 1–10% NaCl, at 15–35°C and was resistant to ampicillin (10μg), carbenicillin (100μg) and oxytetracycline (30μg). The lowest MIC was for enrofloxacine (0.5μgml⁻¹). The in vivo and in vitro toxicity of bacterial cells and the extracellular products (ECPs) of Vh CAIM 1792 grown at 1.0%, 2.0% and 4.0% NaCl were evaluated. Adherence ability, enzymatic activities and siderophore production of bacterial cell was tested. The ECPs exhibited several enzymatic activities, such as gelatinase, amylase, lipase, phospholipase and caseinase. These ECPs displayed a strong cytotoxic effect on HELA cell line at 6 and 24h. Challenges using 10³CFUg⁻¹ caused opacity at the site of injection and over 80% shrimp mortality before 24h p.i. (post-injection). Mortality caused by the ECPs was …