The K-Ras protein is found mutated in 42.4% of lung adenocarcinoma cases, evidencing its importance as a chemotherapeutic target. The Ras protein becomes functional after farnesylation, a post-transduction modification, allowing its attachment to the cellular membrane permitting signal transduction. Perillyl alcohol (POH) has been shown to inhibit the farnesylation of small G-proteins such as Ras. HSP70, a protein known to appear after heat shock (HS), is found over expressed in lung cancer and modifies chemotherapeutic effects. In this work, the effect of POH and HS in the gene expression of human adenocarcinoma lung cells (A549) is studied. Cells incubated with POH followed by 42 degrees C HS presented a 20.7% cellular viability decrease compared to the ones kept at 37 degrees C. A different pattern synthesis was observed for each sequences of cell treatment. Independent of the heat treatment, the amount of HSP70 was decrease by POH without modification in the amount of p53. Here it is shown that HS modified the POH effects in the ERK activation pathway by altering the phosphorylation of p44/42 in human adenocarcinoma lung cells.