DIFFUSION AND ADOPTION OF HEALTH CARE INNOVATIONS IN CARDIOLOGY, IN ARGENTINA. Background: Medicine is changing rapidly and diagnostic and therapeutic innovations are common. Not all professionals adopt these innovations in the same way. Aim: To survey the physicians’ opinions on adopting innovations in cardiovascular health care, to classify individuals from an innovative to a conservative behavior, and to individualize opinion leaders among them, in order to build a social network of influence. Material and Methods: Between November and December 2008, 765 Argentine cardiologists were surveyed via e-mail in Argentina,  to assess the way they adopt and disseminate innovations in cardiovascular health care. Results: The survey was answered by 537 professionals (70.2%). Fifty three percent of respondents were “Early adopters”. However, 63 to 79.3% of respondents preferred to wait for a full demonstration of the usefulness of innovation before adopting it. The opinion leaders’ distribution adopted a scale-free network pattern, where few leaders had many connections and influence on the whole network. The giant component of the network included 41% of physicians; growth simulation of the network showed that the four most popular leaders influenced over 44% of the giant component. Conclusions: Among surveyed physicians there was an attitude towards rapid acceptance of innovations in health care. However, when analyzing the direct opinion of physicians, most cases preferred usefulness demonstrated before accepting innovations. The social network including respondents and opinion leaders showed a scale-free topology with a big influence of a few over the whole network.