Aims: To evaluate the impact of modified atmosphere packaging on in vitro growth of Aspergillus carbonarius and Aspergillus niger, and possible effects on ochratoxin A (OTA) biosynthesis. Methods and Results: Ochratoxigenic isolates belonging to the species A. carbonarius and A. niger were grown on a synthetic grapejuice medium (SNM) and packaged in combinations of controlled O-2 (1% and 5%) and CO2 levels (0% and 15%), and in air as a control. Colony diameters were recorded every 3 days up to 21 days, and OTA was analysed after 7, 14 and 21 days. The greatest reductions in mycelial growth rate were observed at 1% O-2 followed by 1% O-2/15% CO2, whereas 5% O-2 stimulated the growth of all isolates. OTA production by A. carbonarius and A. niger isolates was minimized at 1% O-2/15% CO2 and 1% O-2, respectively, after 7 days of incubation. Maximal OTA accumulation after 7 days was observed for all isolates in the control pack and at 5% O-2. Conclusions: Of the atmospheres tested, only 1% O-2 combined with 15% CO2 consistently reduced fungal growth and OTA synthesis by A. carbonarius and A. niger. Significance and Impact of the Study: Storage under modified atmospheres is unlikely to be suitable as the sole method for OTA minimization and grape preservation; other inhibitory factors are necessary.