The prognostic significance of difficulties in mobility was evaluated using the database of the Helsinki and Vantaa (Finland) ageing studies, in which random persons of four birth cohorts (65, 75, 80 and 85 years, N=1331) were followed for 5 years. Difficulties in walking 0.5 km (15, 33, 43 and 62%), walking indoors (1, 10, 16 and 32%), getting up from bed (4, 15, 19 and 35%) and walking up 10 stairs (14, 28, 41 and 54%) increased in frequency with advancing age. In the age groups of 65, 75 and 80 years, difficulties in mobility were associated with an impaired five-year survival risk, the age-specific risk ratios of death ranging from 1.95 to 5.77. Even minor difficulties in walking outside and walking upstairs increased the mortality risk (age- and gender-adjusted hazard ratios being 1.6 and 1.8, respectively), but did not predict institutionalization. Difficulties in mobility are important risk indicators in an elderly population, but lose their prognostic significance in very old age.