Polyclonal antibodies anti-PfP IgG and anti-PfM IgG and monoclonal antibody MAb29 were prepared to detect a quarantine pathogen of strawberry, Phytophthora fragariae. Laboratory rabbits and mice were immunized using purified and unpurified protein extracts from the mycelial mass of the pathogen. All prepared antibodies were genus-specific, therefore Phytophthora cactorum was also detected. Except for Pythium ultimum, the antibodies did not cross-react with other pathogenic fungi, such as Botrytis cinerea, Colletotrichum acutatum, Fusarium sp., Verticillium albo-atrum. PTA-ELISA was used to test the antibodies. P. fragariae was detected in artificially infected strawberries (cultivars Elsanta, Kama and Vanda) by means of PTA-ELISA, immunoprinting and dot blot. Detection of the pathogen was optimal in undamaged roots or roots with necrotic tips only. At a later stage of infection, when whole roots were necrotic, the crown was more suitable for successful detection. To detect P. fragariae at the early stages of infection it is recommended to use at least two of the three mentioned immunotechniques.