Abstarct: Open-pit mining encounters various technical and economic challenges as the mine deepens. In this regard, during mine design, an acceptable depth for open-pit extraction is determined. Different perspectives have been proposed for determining the open-pit-underground limit. Determining the open-pit-underground limit for deposits with depth extension from the earth's surface and the possibility of both open-pit and underground extraction is one of the first decisions to be made in the mine design process. In this study, the current net present value maximization perspective (Nilsson 1982 solution) has been utilized, and the open-pit-underground limit of the Cheshmeh Hafez lead and zinc mine has been determined, considering uncertainties such as changes in lead and zinc grades. The results indicate that the appropriate open-pit-underground limit for the Cheshmeh Hafez lead and zinc mine is at the 1515-meter elevation.