One problem associated to the study of biochemical diversity of spider venoms is the availability of biological material. Thus, we have constructed a cDNA library from Lasiodora sp venom and screened it by using ELISA technique. The positive clones were characterized by DNA sequencing. The five toxins described have been designated LsTx1 – LsTx5. The Lasiodora sp venom has been shown to contain two pharmacological activities: inhibition of L-types Calcium channel and modulation of Sodium channel gating and kinetics (Kushmerick et. al. 2001). In this work the plasmid pET11a (Novagen^®) was used to express the mature toxin LsTx2. After the PCR reaction of the cDNA using specific primers, competent E. Coli strain BL21(DE3) cells were transformed with the recombinant plasmid. The presence of the appropriate insert was determined using direct colony PCR and DNA sequencing. The transformants were grown in LB-ampicilin medium. Protein expression was induced by addittion of 0,6 mM IPTG. Cell lysates were analyzed by SDS – PAGE and immunoblotting, by using rabbit sera anti-whole venom. The recombinant toxin was purified by reverse-phase chromatography using a C8 column. Proteins were eluted with a continuos acetonitrile / 0,01% TFA gradient. Eluted proteins were monitored at an absorbance of 280 nm and 214 nm. We oberved a peak that represents a pure 5,6 kDa protein. Our results show the activity of the recombinant toxin in ion channels. The cDNA sequence was also expressed in pQE31 vector. The aim is to facilitate the detection and purification of 6xHis-tagged protein. We don't know yet if the His-Tag will affect the protein activity.