OBJECTIVE: Recent studies have investigated visual analogue scales (VAS) as an alternative to the Lake Louise AMS Self-Report Score (LLS) for the self-assessment of acute mountain sickness (AMS). We investigated their use in adolescents. METHODS: The study was conducted during the 2009 and 2010 British Schools Exploring Society 35-day expeditions to Ladakh. Comparable ascent profiles were followed, reaching a maximum altitude of 6000 m. LLS and VAS AMS scores were recorded each morning. VAS comprised 100 mm lines for each LLS symptom; VAS scores were summed to give a composite daily total (VAS(c), expressed as a percentage). In 2010, an additional line was used to score overall "altitude sickness' (VAS(o)). RESULTS: 42 individuals participated in 2009 (83% compliance; mean age 17.4 years); 28 in 2010 (82% compliance; 17.5 years). 759 data points were recorded in 2009; 529 in 2010. There was a significant correlation between LLS and VAS(c) on both expeditions (rho=0.80, p<0.001 in 2009; rho=0.65, p<0.001 in 2010). These significant correlations remained when cases of AMS were analyzed separately. However, in all cases, the relationship between LLS and VAS was distorted, with a tendency for VAS to underscore symptoms of AMS when LLS<5. A VAS(c) value of 5.5% had an 82% specificity and sensitivity for all cases of AMS; VAS(c) of 9.5% had a 90% specificity and sensitivity for moderate and severe AMS. CONCLUSIONS: Whilst adolescents are capable of self-monitoring for AMS using VAS, the relationship with LLS is distorted. The LLS, despite its limitations, therefore remains the preferred method for the self-assessment of AMS in adolescents.