The acid phosphatase and hemagglutinating activities of four species of <em>Cucurbitaceae</em> were determined during seeds germination and seedlings development. In all cases traces of enzyme and hemagglutinating activities were found in dry and imbibided seeds. In developing seedlings of <em>Cucumis sativus</em> the activities increased to maximum on the 3rd day while in other species on the 6th day of germination and than fell down. Dot blot and Western blot techniques have shown that in seeds and seedlings of all investigated species present were proteins which cross-reacted with antibodies raised against lectins: CLBa and Con A. It has been shown that proteins from seeds and seedlings of <em>Cucurbita maxima</em> var. <em>bambino</em>, <em>Cucurbita pepo</em> var. <em>giromontia</em> and <em>Cucumis sativus</em> had more pronounced antigenical similarity to lectin CLBa (from <em>Cucurbitaceae</em>) than Con A, while proteins from cotyledons of <em>Cucurbita pepo</em> var. <em>patissonina</em> reacted better with antibodies raised against Con A (the lectin from <em>Papilionaceae</em>) than with CLBa.