We explore how molecular techniques can be applied to ostracod DNA to infer past climatic and environmental fluctuations at several time scales. Cladoceran DNA has been extracted from resting eggs up to several thousand years old but no such work onOstracoda has yet been published.Ostracod eggs are not encased in large protective ephippia as in Cladocera, and only some are pro- tected by thick walls. Collapsed eggs with thin walls will be more difficult to sort individually from sediments; direct extraction of DNA is likely to work only on thick-walled eggs, but could also be possible fromjuveniles hatched fromeggs several hundred years old. The potential for direct extraction of DNA fromfossils (valves, remnant soft parts) is considered. A potential method to infer large climate-induced effects on ancient lakes (e.g. large lake-level fluc- tuations) involves DNA analyses of extant populations, combining phylogenetic and population genetic (coalescent) techniques.