Background More than seven out of 10 Dutch construction workers describe their work as physically demanding. Ergonomic measures can be used to reduce these physically demanding work tasks. To increase the use of ergonomic measures, employers and workers have to get used to other working methods and to maintaining them. To facilitate this behavioural change, participatory ergonomics (PE) interventions could be useful. For this study a protocol of a PE intervention is adapted in such a way that the intervention can be performed by an ergonomics consultant through face-to-face contacts or email contacts. The objective of this study is to evaluate the effectiveness of the face-to-face guidance strategy and the e-guidance strategy on the primary outcome measure: use of ergonomic measures by individual construction workers, and on the secondary outcome measures: the work ability, physical functioning and limitations due to physical problems of individual workers. Methods/Design The present study is a randomised intervention trial of six months in 12 companies to establish the effects of a PE intervention guided by four face-to-face contacts (N = 6) or guided by 13 email contacts (N = 6) on the primary and secondary outcome measures at baseline and after six months. Construction companies are randomly assigned to one of the guidance strategies with the help of a computer generated randomisation table. In addition, a process evaluation for both strategies will be performed to determine reach, dose delivered, dose received, precision, competence, satisfaction and behavioural change to find possible barriers and facilitators for both strategies. A cost-benefit analysis will be performed to establish the financial consequences of both strategies. The present study is in accordance with the CONSORT statement. Discussion The outcome of this study will help to 1) evaluate the effect of both guidance strategies, and 2) find barriers to and facilitators of both guidance strategies. When these strategies are effective, implementation within occupational health services can take place to guide construction companies (and others) with the implementation of ergonomic measures. Trail registration Trailnumber: ISRCTN73075751, Date of registration: 30 July 2013.