A liquid chromatographic method for isolating ecdysteroids from crab tissues and crustacean tissue culture media is reported. The method employs commercially-available Sep-Pak C18 cartridges containing a reversed phase packing that retains ecdysteroids. The technique is simple and rapid; it typically yields recoveries in the range of 85-90% for extractions of tissues, and 90-95% for extractions of media. © 1982, Taylor & Francis Group, LLC. All rights reserved.