A novel thermostable lectin, called DdeL, was obtained from the extract of Dypsis decaryi seeds. The extract of the tegument had the highest specific hemagglutination activity (196.03 HA/mg) when subjected to 70% acetone precipitation and purification on Superdex G-75 and exhibited a single peak (38.8 kDa). DdeL, a glycoprotein, had agglutinated blood types and was inhibited only by glycoproteins (albumin, azoalbumin and azocasein). Biochemical properties showed higher activity at acid pH (pH 5-6) than alkaline pH and activity was observed at all temperatures (up to 100 degrees C). DdeL exhibited bacteriostatic activity against Providencia swarth and Staphylococcus aureus ATCC 29213, which presented minimum inhibitory concentration (MIC) of 750.0 mu g/mL. When tested against fungi Sporotrichum schenckii and Candida albicans showed excellent MIC50 at 0.52 and 2.06 mu g/mL, respectively. DdeL showed no cytotoxic effect on macrophages (J774.A1) and renal embryonic cells (HEK-293). in vitro acaricide activity of DdeL against Rhipicephalus showed high activity in low concentration. Therefore, we conclude that DdeL may be of interest for potential biotechnological applications.