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In addition to being one of the most productive upwelling systems, theoceanic region off Peru is embedded in one of the most extensive oxygenminimum zones (OMZs) of the world ocean. The dynamics of the OMZ off Peruremain uncertain, partly due to the scarcity of data and to the ubiquitousrole of mesoscale activity on the circulation and biogeochemistry. Here weuse a high-resolution coupled physical/biogeochemical model simulation toinvestigate the seasonal variability of the OMZ off Peru. The focus is oncharacterizing the seasonal cycle in dissolved O<sub>2</sub> (DO) eddy flux at theOMZ boundaries, including the coastal domain, viewed here as the easternboundary of the OMZ, considering that the mean DO eddy flux in these zoneshas a significant contribution to the total DO flux. The results indicatethat the seasonal variations of the OMZ can be interpreted as resulting fromthe seasonal modulation of the mesoscale activity. Along the coast, despitethe increased seasonal low DO water upwelling, the DO peaks homogeneouslyover the water column and within the Peru Undercurrent (PUC) in australwinter, which results from mixing associated with the increase in both theintraseasonal wind variability and baroclinic instability of the PUC. Thecoastal ocean acts therefore as a source of DO in austral winter for the OMZcore, through eddy-induced offshore transport that is also shown to peak inaustral winter. In the open ocean, the OMZ can be divided vertically into twozones: an upper zone above 400 m, where the mean DO eddy flux is larger onaverage than the mean seasonal DO flux and varies seasonally, and a lowerpart, where the mean seasonal DO flux exhibits vertical–zonal propagatingfeatures that share similar characteristics than those of the energy fluxassociated with the annual extratropical Rossby waves. At the OMZ meridional boundaries where the mean DOeddy flux is large, the DO eddy flux has also a marked seasonal cycle thatpeaks in austral winter (spring) at the northern (southern) boundary. In themodel, the amplitude of the seasonal cycle is 70 % larger at the southernboundary than at the northern boundary. Our results suggest the existence ofdistinct seasonal regimes for the ventilation of the OMZ by eddies at itsboundaries. Implications for understanding the OMZ variability at longertimescales are discussed