Objectives: The objectives of this study were to assess whether the Envirovet programme served to increase the number of practising ecosystem health professionals, as well as to measure the lasting professional and personal impact of the programme on participants. Design: Impact programme evaluation. Setting: An emerging strategy among global health programmes is to promote "One Health"--namely, the understanding that human, animal and environmental health are inextricably linked--as a unifying framework of coordinated education, research and practice. Established in 1991, the Envirovet Summer Institute was created to increase worldwide knowledge and capacity of veterinary medicine students and practitioners to support ecosystem health as a critical component of the One Health approach. Method: A semi-structured questionnaire was electronically administered to past programme participants. Results: The majority of respondents (65 of 88, 74%) indicated that they had held an ecosystem health employment position since their participation in Envirovet. The reach of Envirovet went beyond participants' own experiences, by influencing local organisations, programmes, colleagues, family and friends. Furthermore, Envirovet reportedly inspired past participants to make environmentally conscious lifestyle choices and spurred them to make changes professionally, including guiding on-the-job decisions and strengthening network contacts. Conclusion: Envirovet offers an established example of One Health training. Additional educational programmes might usefully include One Health principles coupled to a comparable evaluation plan to establish a larger, more comprehensively trained and increasingly effective global health workforce.