The lectins are ubiquitous protein in the nature that reversibly bind to mono, oligo, polysaccharides and glycoconjugates. They do not present catalytic activity and unlike antibodies, are not products of immune reply. The aim of the present work was to evaluate the extraction and back-extraction of a lectin from Crataeva tapia bark using the reversed micellar system of sodium di(2-ethylhexyl)sulfosuccinate (AOT) in isooctane. The Crataeva tapia bark was collected in the region of Recife city (Pernambuco, Brazil) and the extract [10 % (w/v) in 150 mM NaCl] was obtained by trituration and agitation for 16 h at 4 ^oC, filtered on gaze and centrifuged (4.000 x g for 15 min). The supernantant obtained was called crude extract (CE). The factors that affect the protein extraction, such as: agitation contact time (5 - 20 min), ionic strength, salt type (NaCl, KCl e CaCl₂) and concentration (30 – 300 mM) included, pH of aqueous phase (pH 3.0 –12.0) and surfactant concentration (5 - 100 mM AOT), were investigated. For the back-extraction the following parameters were evaluated: pH of aqueous phase (pH 5.0 – 7.0) and ionic strength (50 - 1000 mM KCl) being added to the system 5 % of Butanol. The parameters, agitation speed (900 rpm), temperature (25^oC) and protein concentration (0.374 mg/ml), were maintained constant in all experiments. The best results for the extraction were obtained with 5 min of contact time between the two phases, 30 mM of NaCl, citrate/phosphate buffer, pH 5.5 and 5 mM of AOT, where it was possible to obtain 70% of protein extraction. For the back-extraction, the best conditions were; citrate/phosphate buffer, pH 5.5 added by 1000 mM of KCl, where it was possible to obtain a protein recovery of 80.65% (CE) with 50% of hemagglutinating activity. Samples from the best conditions of extraction and back-extraction revealed only one single PAGE band for basic protein and two SDS-PAGE bands. These results showed the efficiency of the reversed micellar system in the lectin purification.