Background: The variations of the olfactory fossa/ethmoid roof are common. These variations are important to be acknowledged when dealing with endoscopic sinonasal and skull base surgeries due to possibilities of injuries to the vital structures. The depth of the olfactory fossa is classified as Keros type I, II, or III (Depth 1-3mm, 4-7mm, and 8-16mm, respectively). Keros type III is consider the most venerable type to iatrogenic injury followed by type II. The variations can be similar or dissimilar among countries, geographies, and ethnicities. Functional endoscopic sinus surgery (FESS) is currently the preferred surgical option worldwide when dealing with nasal or sinonasal diseases. Awareness of the anatomical landmarks, Variations in the depth of the olfactory fossa, assist the surgeon in avoiding CSF leaking, brain herniation, and hemorrhage. For a few decades, it was introduced in Africa (Egypt, Nigeria, South Africa, Kenya, etc.). FESS was introduced at the Muhimbili National Hospital, Tanzania in 2010 and is currently becoming widely practiced in the country. Only a single study done in Kenya on anatomical variations of the ethmoid roof was found in east Africa. No data was found in Tanzania and due to the scarcity of data in Africa especially in east Africa, this study was necessary.