||Plants have long been used as a cure for several diseases; recently there have been renewed interests into the plants as a source of new drug molecules. Gynandropsis gynandra (Nyar) is used for several purposes except for cancer treatment while Piper methysticum (Dek) is a known toxic plant. This research showed that both plants posses antiproliferative effects on human lung and stomach cancer cells. Nyar was separated into 3 fractions A,B and C with fraction B showing highest activity at concentrations greater than 1300μg/ml on gastric cancer cells(AGS) and an IC 50 of 650μg/ml on lung cancer cells(A549). Dek exhibited cytotoxic activity on both cell lines with IC 50 concentrations of 5μg/ml and 10μg/ml on AGS and A549 respectively. Techniques used in this research included cell counting, monitoring caspase activity, DNA quantification and MTT assay.