Celebrating 30 years of the international network of agencies for health technology assessment (INAHTA).

It is not often that international collaborations are sustained for any significant period, let alone for three decades. However, despite relying on largely voluntary contributions of individuals within its member institutions, the International Network of Agencies for Health Technology Assessment (INAHTA) has not only been an example of sustained collaboration over 30 years but also an example of how an initially modest collaboration can grow and thrive. Current and former serving Chairs and secretariat of the Network have come together to review network documents and outputs and reflect on the history of INAHTA, since its inception in Paris in 1993. Building on the paper from Hailey et al 2009 that documented the growth of the network after 15 years, we have considered and documented the factors that we believe have helped sustain the network and enable it to flourish in the subsequent 15 years. We have also considered the various challenges experienced along the way, as these too can aid in making a collaboration stronger. Future directions for the network have also been contemplated, given the evolving nature of HTA and the regional collaborations that have recently emerged. We hope that by sharing the lessons learned from this living example of international global collaboration relationships between like-minded organizations can be similarly fostered and enhanced into sustainable collaborations, for the benefit of all.