The susceptibility of different stages of the potato tuber moth, Phthorimaea operculella, to different modified atmospheres containing various concentrations of ozone was studied as an alternative to methyl bromide fumigation. The ozone concentrations used against larvae and adults were 5, 10, 20 40, 60 and 80 ppm at different exposure times. For the eggs and pupae, a range of 1 to 5 ppm of ozone was used. Results showed that 5 ppm was adequate to kill all eggs and pupae of the moth. The exposure time needed to achieve a 100%mortality of eggs and pupae was 1 h, whereas exposure at 80 ppm for 1 h caused 80 and 84%mortality of larvae and adults of P. operculella, respectively. The order of sensitivity of P. operculella to ozone was: eggs > pupa > adults and larva. In conclusion, the eggs and pupae of potato tuber moth were more sensitive to modified atmosphere than larvae and adults. The results showthat ozone could be an effective alternative to control potato tuber moth in the storage.