Abstract: The allozymic diversity was preliminarily investigated for 72 samples of rare and endangered species Isoetes sinensis Palmer, using isoelectric focusing in thin-layer polyacrylamide slab gels. 24 enzyme systems were initially screened, resulting 13 workable enzyme systems. A total of 27 alleles of 16 loci were detected from 7 well-resolved enzymes. Although 12 loci were observed to be polymorphic in ex situ conserved populations at Wuhan Botanical Garden, the overall genetic diversity is low in I. sinensis. The study provided preliminary evidence that a comprehensive conservation and restoration program is needed for sustainable conserving and recovery of natural I. sinensis populations. A further study of I. sinensis population and conservation genetics is urgently needed by employing more sensitive molecular methods.