Specimens of <i>Australocypris robusta</i> collected at different seasons from Lake Keilambete in western Victoria, Australia were assayed for strontium and calcium content, and the molar strontium/calcium ratio was correlated with the salinity at various temperatures. Paleosalinities of Lake Keilambete for the past 10,000 years were calculated from the ostracod (<i>A. robusta, Mytilo cypris praenuncia, Leptocythere lacustris</i>, and <i>Dicypris compacta</i>) strontium/calcium ratio of fossil material, and were in striking agreement with independent interpretations of the paleosalinity. The range of salinity spanned 14-95per thousand. -- AATA