People living with cystic fibrosis (CF) are believed to perform poorly at high altitude. The advent of cystic fibrosis transmembrane conductance regulator (CFTR) modulators has transformed patient care, making high-altitude trekking an attainable goal for most patients living with CF. We consider how an amateur trekker with CF who wishes to climb a high mountain such as Kilimanjaro (5895m) should be advised. Since symptomatic pulmonary hypertension is a contraindication to high altitude travel, CF patients with pulmonary hypertension should use supplemental oxygen and take nifedipine for HAPE prophylaxis. There is no contraindication to the use of prophylactic acetazolamide in CF. With the success of CFTR modulators, it may no longer be necessary to optimise the CF patient’, s clinical status with an inpatient course of intravenous antibiotics in advance of high-altitude travel. High-altitude trekkers with CF should use volumatic spacers with their inhalers and portable nebulisers. They should continue to take their regular medications, including mucolytic agents and prophylactic oral antibiotics. Monitoring oxygen saturation using a pulse oximeter may be useful. On the Kilimanjaro trek, a longer climbing route such as Lemosho is preferred as it allows more time for ACCLIMATISATION to hypoxia. A formal medical fitness-to-travel assessment by a respiratory physician may be mandated by insurance companies. Close liaison between respiratory and travel medicine specialists will best serve the needs of high-altitude trekkers with CF.