Over the past 10 to 20 years, endoscopic endonasal surgery has become for many teams the preferred treatment for sinonasal tumors. Technical advances in the field of surgical instrumentation (good visualization, hemostasis…) and the progress of imaging guidance (to avoid neurovascular complication) has made those procedures simpler and safer. Nevertheless, endonasal endoscopic procedures require a trained surgical team of ENT specialist and neurosurgeon. Endoscopic endonasal surgery has been reported to be feasible for all types of sinonasal tumors whether benign tumors such as inverted papillomas, or malignant tumors. In this paper, we mostly focus on the principles underlying the transcribriform approach, which is dedicated to the surgery of CSF leaks, encephaloceles/meningoceles, access to benign intracranial tumors such as olfactory groove meningiomas, and the resection of sinonasal malignancies with skull base invasion such as olfactory neuroblastomas.