In recent years, the National Healthcare Services worldwide are forcing to implement spending review processes, to improve inefficiency areas and free up economic resources. Thus, the purchasing process, which have been centralized at regional and national level, require an in-depth optimisation. The present contribution aims at investigating the knowledge assets that might influence the design of a Complexity Index for Tender Procedures (CITP), useful to manage this topic in the public healthcare sector. A literature review was performed for the identification of all the relevant assets to be considered in the design of a model for the CITP in healthcare. At first, a focus group, with 7 domains experts and 3 academic researchers was conducted, in order to define the variables affecting the CITP. A Delphi method was also implemented, to decline the variables and their relationships, thus defining the contribution of each variable and item, useful to develop the CITP framework. Once having created the CITP construct, a hierarchical sequential linear regression model was implemented to define the predictors of the dependent variables and validate the model. The evaluation of the robustness of CITP result was assessed by means of a bootstrapping approach. According to the above, the presence of a tender preliminary phase, the number of batches and companies involved in a tender procedure, as well as the award criteria and the tender economic amount, were the main knowledge assets impacting on the CITP design. Results show the robustness of the CITP framework developed, with an Adj R² always higher than 80%: in particular, the tender preliminary phase, the number of companies, the economic amount, as well as the moderator effect of the criteria award on batches dependent variable and number of companies, mostly explained the complexity of tender. The CITP could be a useful support for any kind of technological batch tenders, given the variation lower than 5%, for any typology of batches. The present study also confirmed the possibility to create validated scales by means of sum of items explaining the same topics as happened in other operational and innovation settings.