This present study describes the isolation of a high molecular weight fraction (F1) from the venom of the social spider Parawixia bistriata, by gel filtration and also its subfractions by further purification with affinity chromatography on a Concanavalin A-Sepharose column. Acid and an alkaline phosphatase activities were found in fractions. The effects of pH, temperature and metallic ions on these activities were evaluated. Optimal temperature for both enzymes was 55 degrees C and optimal pH was 5.0 and 8.5 for the acid and alkaline phosphatase activities, respectively. As ZnCl(2) inhibited enzymatic activities and the chelating agent ethylenediaminetetracetic acid (EDTA) raised the basal phosphatase activities, it was speculated that the venom itself could contain Zn(+ +); this was confirmed with the use of an atomic absorption flame spectrometer. In conclusion, the high molecular weight components of the spider venom of P. bistriata have acid and alkaline phosphatase activities, which may reflect the presence of at least two different enzymes.