This study aimed to evaluate whether a stair-promoting signed intervention could increase the use of the stairs over the elevator in a health-care facility. A time-series design was conducted over 12 weeks. Data were collected before, during and after displaying a signed intervention during weeks 4-5 and 8-9. Evaluation included anonymous counts recorded by an objective unobtrusive motion-sensing device of people entering the elevator or the stairs. Self-report data on stair use by hospital staff were also collected. Stair use significantly increased after the first intervention phase (P = 0.02), but after the intervention was removed stair use decreased back towards baseline levels. Moreover, stair use did not significantly change after the re-introduction of the intervention. Lastly, stair use decreased below the initial baseline level during the final weeks of evaluation. Furthermore, there was no significant change in self-reported stair use by hospital staff. Therefore, the signed intervention aimed at promoting an increase in incidental physical activity produced small brief effects, which were not maintained. Further research is required to find more effective 'point of choice' interventions to increase incidental physical activity participation with more sustainable impact.