The gene psbA,encoding the key photosynthetic system D1 protein,was recemly found in the genomes of phages infecting marine Synechococcus and Prochlorococcus and in environmental clones obtained from various aquatic systems.With culture-independent PCR and Sanger sequencing methods,we surveyed the diversity and distribution of cyanophage psbA genes existing in two paddies of Northeast China by an incubation experiment.