Semi-supercentenarians, or people who reach 105 years of age, are regarded as model cases for 'successful ageing'. Semi-supercentenarians maintain capability and cognition for longer than the centenarians who died between 100-104 years of age, together with postponed frailty or age-related diminution of multiple organ reserve. Understanding the biological factors determining extreme longevity and compression of morbidity might help to achieve extended healthy life span for the wider population.