Mint oil production from peppermint (Mentha × piperita) is a new industry in the river valleys of north-east Victoria, Australia. In this study, the disease cycles on M, × piperita, M. × gracilis (Scotch spearmint) and M. spicata (spearmint) growing in the Ovens Valley, north-east Victoria, were monitored for four years. The complete life cycle was observed annually on M. × gracilis and M. spicata, but only urediniospores and teliospores were observed on M. × piperita. Viable urediniospores were always present on M. × piperita, confirming that urediniospores carry the disease over winter on peppermint grown in north-east Victoria. On the two spearmint species, viable urediniospores were observed only on M. × gracilis during the 1997 winter. Reports on the disease cycle of P menthae in the mint-growing regions of the United States of America, the United Kingdom and New Zealand have shown that P. menthae is macrocyclic, with teliospores as the mechanism for overwintering, but the present study concludes that it is microcyclic on peppermint growing under local conditions.