We studied the population genetic structure of nine bisexual Artemia sinica populations from the provinces of Inner Mongolia, Shanxi and Qinghai in China, using variation at nine allozyme loci (cellulose acetate electrophoresis). There is a clear-cut tendency for an increase in genetic variation, as measured by heterozygosity, with increasing habitat size. Although we observe a positive relationship between genetic differentiation and geographical distance, overall FST values are low: populations separated by approximately 1000 km show average FST values of 0.05-0.1, whereas populations separated by 100 km show no genetic differentiation at all.