The present paper deals with biological studies of natural salt lakes located in the Rajasthan. There were investigated for first time the halophilic microorganisms (bacteria and archaea) and also phyto- and zooplankton species in relation with physical-chemical parameters as control factors. The chemical composition of all tested stations is marked by the abundant presence of chlorides (sodium, magnesium, potassium) and also some relatively important concentrations of aluminum. The biological diversity was represented by several types of archaea and halophilic bacterial species and some species of cyanobacteria and diatoms. There were also identified ciliates, rotifers and copepods mainly in the samples taken from Sambhar Lake. The results revealed the presence of magnesium and calcium ions and a chloride content that influences the phytoplankton and zooplankton diversity in these saline environments.