The onset of bathing disability among older people is critical for a decline in functioning and has implications for both the individuals' quality of life and societal costs. The aim of this study was to evaluate long-term cost effectiveness of an intervention targeting bathing disability among older people. For hypothetical cohorts of community-dwelling older people with bathing disability, transitions between states of dependency and death were modelled over 8 years including societal costs. A five-state Markov model based on states of dependency was used to evaluate Quality-adjusted life years (QALYs) and costs from a societal perspective. An intervention group was compared with a no intervention control group. The intervention focused on promoting safe and independent performance of bathing-related tasks. The intervention effect, based on previously published trials, was applied in the model as a 1.4 increased probability of recovery during the first year. Over the full follow-up period, the intervention resulted in QALY gains and reduced societal cost. After 8 years, the intervention resulted in 0.052 QALYs gained and reduced societal costs by €2410 per person. In comparison to the intervention cost, the intervention effect was a more important factor for the magnitude of QALY gains and long-term societal costs. The intervention cost had only minor impact on societal costs. The conclusion was that an intervention targeting bathing disability among older people presents a cost-effective use of resources and leads to both QALY gains and reduced societal costs over 8 years.