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Previous studies from single centres or single-surgeon series report good early and mid-term results for high tibial osteotomy (HTO) in the treatment of osteoarthritis of the knee. However, the survivorship of HTO at a national level is unknown. This registry-based study included 3195 high HTOs performed between 1987 and 2008. Kaplan-Meier analysis revealed an overall survivorship of 89 % (95 % confidence interval (CI) 88 to 90) at five years and 73% (95 % CI 72 to 75) at ten years, when conversion to total knee replacement was taken as the endpoint. Females and patients aged> 50 years had worse survivorship than males or patients aged ≤ 50 years (hazard ratio (HR) 1.26 (95 % CI 1.11 to 1.43) and HR 1.41 (95 % CI 1.2