BACKGROUND: Population strategies to increase physical activity are an essential part of cardiovascular disease prevention. However, little data exist on lifestyle interventions that are easy to integrate into everyday life such as using stairs instead of elevators at the workplace. DESIGN: Pre and postintervention study. METHODS: A 12-week promotional campaign for stair use consisting in posters and floor stickers at the point of choice between stairs and elevators at each hospital floor was organized in a university hospital building. In 77 selected employees with an inactive lifestyle, physical activity, aerobic fitness, anthropometrics, blood pressure, lipids, insulin sensitivity, and C-reactive protein were assessed at baseline, 12 weeks, and 6 months. RESULTS: During the intervention median daily number of ascended and descended one-story staircase units was 20.6/day (14.2-28.1) compared with 4.5/day (1.8-7.2) at baseline (P<0.001). At 12 weeks, estimated maximal aerobic capacity had increased by 9.2+/-15.1% (P<0.001) corresponding with approximately 1 MET. There were significant declines in waist circumference (-1.7+/-2.9%), weight (-0.7+/-2.6%), fat mass (-1.5+/-8.4%), diastolic blood pressure (-1.8+/-8.9%), and low-density lipoprotein cholesterol (-3.0+/-13.5%). At 6 months, the median daily number of ascended and descended one-story staircase units had decreased to 7.2 (3.5-14.0). Benefits on estimated maximal aerobic capacity (+5.9+/-12.2%, P=0.001) and fat mass (-1.4+/-8.4%, P=0.038) persisted. CONCLUSION: Encouraging stair use at work is effective for improving fitness, body composition, blood pressure, and lipid profile in asymptomatic individuals with an inactive lifestyle and thus may be a simple way to significantly reduce cardiovascular disease risk at the population level.