Background Studies show that the well-prepared traveller is less likely to suffer travel related illness. This study is designed to examine trekkers' knowledge of altitude sickness in an attempt to see whether knowledge can protect against acute mountain sickness (AMS) and high altitude pulmonary or cerebral oedema (HAPE/HACE). Methods A convenience sample of 130 trekkers were interviewed in the Solu Khumbu region of Nepal. They were asked what action they would take firstly if they developed symptoms of AMS, and secondly, symptoms of HAPE/HACE whilst ascending. Options were to continue up, stay at the same altitude, descend or ask their guide. Results With symptoms of moderate to severe AMS, 37 trekkers (28 per cent) indicated they would continue their ascent while 113 (72 per cent) would not. Those individuals who proposed continued ascent were significantly more likely to be suffering from symptoms of AMS (p = 0.025) and had ascended significantly more rapidly over the preceding 72 h (p = 0.004) then those who proposed to halt their ascent. With regard to symptoms of HAPE/HACE, 12 (9 per cent) indicated they would not descend, demonstrating no association with AMS (p = 0.07) or ascent in preceding 72 h (p = 0.7). Conclusion Trekkers who indicated that they would act safely in the event of developing moderate to severe AMS were significantly less likely to be suffering from AMS when interviewed and had ascended significantly less altitude in the preceding 72 h being more likely to adhere to recommended ascent guidelines.