Field surveys were conducted in order to collect information on the occurrence of wild Artemia populations in hypersaline environments such as salt lakes, lagoons and salty rivers. The mating behaviour of Artemia populations and the presence or absence of males were carefully recorded. Sampling involved the use of plankton nets. Collected cysts were characterized on the basis of their diameter and chorion thickness, while nauplii (instar-I) were characterized on the basis of their total length. Artemia populations were found at 17 different geographical locations scattered over 12 Iranian provinces. All Iranian Artemia populations are parthenogenetic with the exception of Artemia urmiana from Urmia Lake. During the last five years severe salinity increase has caused a dramatic reduction of population sizes in several hypersaline settings in Iran. The study of cyst and naupliar biometry revealed substantial differences between populations and can be used, to some extent, for their discrimination. Cyst diameter mean values range from 243.2 to 285.4 μm. For some Iranian parthenogens, cyst diameters were among the smallest recorded so far for parthenogenetic Artemia. The total length of newly hatched nauplii ranges from 455.5 to 529.8 μm.