The trekking ascent to Point Lenana (4,985m) on Mount Kenya is a popular objective for soldiers on adventurous training in Kenya. The standard route previously taken has been the Naro Moru route which involves an ascent rate far in excess of that recommended to avoid altitude illness. This article describes the case of a British soldier who developed high altitude cerebral oedema during an ascent of Point Lenana via the Naro Moro route. Recommendations to reduce the risk of altitude illness on Mount Kenya include alternative and more gradual routes of ascent. Early symptom recognition and descent are vital to prevent clinical deterioration.