Edible and nonedible grades of virgin olive oil (VOO), differing in quality characteristics, were evaluated for potential genotoxicity in the Drosophila somatic mutation and recombination test (SMART) before and after heating at high temperatures. Drosophila larvae were fed on medium containing 6 and 12% v/v of each of the examined oils. Edible VOOs did not exhibit any mutagenic or recombination activity even after thermal treatment. Lower grade VOO gave negative results at the concentration of 6% and inconclusive ones at 12%. However, after its thermal treatment, a statistically significant increase of large single spots was observed, giving a positive result for this spot category at both concentrations. Evaluation of the possible contribution of olive phenolic compounds to the nongenotoxic effects observed was carried out using a polar olive leaf extract and pure oleuropein. No significant increase in the frequency of any category of mutant spots was recorded for leaf extract (0.8-12 mg of total polar phenols/dose) or pure oleuropein (0.8-8 mg/dose). These results are expected to contribute to the ongoing interest in the inherent properties of VOO as part of the everyday diet.