Observations were made on an isolate of Phytophthora cinnamomi from highbush blueberry in comparison with other isolates of the fungus, including the type culture. In most of the isolates, sex organs developed in abundance in pure culture on oat grains. An interesting feature was the occurrence of bicellular antheridia in approximately equal numbers with unicellular types. Sex organs were not produced in dual culture with P. cryptogea.