In this paper, we report the effect of standard NDGA, as compared to that of an aqueous extract of Larrea divaricata Cav., on BW 5147 lymphoma cell-line proliferation. To determine the mechanism of action, the effects of both on the level of intracellular cAMP, protein kinase C activity and calcium influx were studied. Moreover, the NDGA present in the aqueous extract of the plant was quantified. The aqueous extract and the standard NDGA showed antiproliferative action against these cells. While the antiproliferative activity of the aqueous extract was mediated by an increase in cAMP levels, and inhibition of PKC and calcium influx, the antiproliferative activity of NDGA was related only to the inhibition of PKC. Considering the amount of NDGA detected in the aqueous extract of the plant, at the concentrations analyzed in this case, antiproliferative activity of Larrea divaricata cannot be attributed to this compound, but could have an additive effect on the activity of other compounds.