Three sources of surface irrigation water in the Nablus area were assayed during Jun. 1985-Mar. 1986 for the presence of Phytophthora spp. using millipore filtration and a selective medium. Five potentially pathogenic P. spp. were detected: P. cryptogea, P. citrophthora, P. nicotianae var. parasitica, P. palmivora and an unidentified P. sp. The importance of these fungi in relation to disease incidence in citrus orchards is discussed.