Abstract : Maxillary premolars often have complicated anatomies with one to three roots and two to four root canals. These complications are compounded because the root canals on resected surfaces during apicoectomy may differ depending on the locations and resected angles. In this paper, two cases of apicoectomy in maxillary premolars with complicated root canal anatomy on the resected surfaces are described and discussed. The surgery was performed using an operating microscope and biocompatible root-end filling materials. Microsurgical approaches with a better understanding of root canal anatomy can lead to more predictable outcomes in the healing of apical lesions.