Health Technology Assessment aims to evaluate the real and/or potential effects of a given health technology and the consequences that the introduction or exclusion of an intervention can have on the healthcare system, the economy, and society. HTA can guide choices regarding the clinical and economic utility of health technologies through creating a direct link with the scientific evidence of the EBM world. In physiotherapy, HTA studies are still very limited due to the heterogeneity of the variables in question. We asked Johan Lambeck, an internationally renowned physiotherapist specialized in hydrotherapy, to give us his view on the dual concept of efficacy-efficiency as it pertains to his field of hydrotherapy.