OBJECTIVES Stair climbing (SC) as daily activity is assessed with different SC-tests, but none directly measures ground reaction force over several steps. The Leonardo Mechanograph Stair A has five steps and four force sensors. This study aimed at investigating the reliability of the Stair A test for force, power and time to SC. METHODS 55 healthy participants (age: 48±14 years) were five times tested during SC with self-chosen and fast speed. 30 participants were examined for test-retest-reliability, calculated with the intraclass correlation coefficient (ICC). The variability was examined with the coefficient of variation (CV). To determine potential associations between SC and jumping performance or daily activity, squat and countermovement jumps were additionally performed and the International physical activity questionnaire (IPAQ) was completed. RESULTS The inter-visit ICCs of self-chosen and fast SC were good to excellent 0.63-0.77. The intra-visit ICCs were excellent after three trials (0.78-0.88). The CVs for SC with self-chosen speed were lower (2.1-6.6%) than those for fast SC (4.9-10.8%). There were no significant correlations between SC and jump parameters and only moderate correlations with the IPAQ. CONCLUSION The Stair A is a reliable tool for the assessment of SC.