Mushrooms comprise an unlimited source of active compounds that have beneficial health effects without known negative side effects and can potentially be used as important therapeutic products against cancer, which is the leading cause of death worldwide. In this study we investigated the cytotoxic, antiproliferative, apoptotic, and antiinvasion effects of Macrolepiota procera, which is valued as an edible and medicinal mushroom, on A549 lung cancer cells. The cytotoxic effect of the M. procera extract was determined by using the XTT method. Total RNA was isolated from cells with TRI Reagent to determine the apoptotic effect of the extract, after which complementary DNA was synthesized. Expression profiles of the target genes were determined by quantitative reverse-transcriptase polymerase chain reaction, and protein changes were determined by using Western blotting. We used the TUNEL assay to evaluate the apoptotic effects of the M. procera extract. Effects of M. procera on cell invasion were investigated by using a Matrigel chamber assay. The half-maximal inhibitory concentration of the M. procera extract was determined to be 2 mg/mL against A549 lung cancer cells at 72 hours. According to our results, expression of Cyclin D1, CDK4, CDK6, Bcl-2, Akt, and NOXA genes significantly decreased and that of Bax, Caspase-3, Caspase-9, PTEN, PUMA, p21, and p53 increased in cells from the dose group compared with their expression in control cells. According to the results of the TUNEL assay, 28 +/- 3.6% of cells were apoptotic in the dose group. The M. procera extract also reduced invasion in A549 cancer cells. The results suggest that M. procera has an antiproliferative effect in a dose- and time-dependent manner.