Traditional measures of the impact of published research, such as citation counts, are limited to measuring academic impact. The use of social media and other online tools as alternative measures of research impact is gaining popularity and used by leading medical journals. MEDLINE was searched for articles published with subject headings relating to solid organ transplantation between August 1, 2011, and July 31, 2012. Citation data were retrieved from SCOPUS, and statistics regarding mentions in social media, social bookmarking sites, news outlets, and expert recommendation sites were retrieved from the data at www.altmetric.com. Data were analyzed for associations between alternative metric data and citation rates. The search retrieved 6,981 publications. Sixty-six percent of the articles had at least one citation. Mentions in social media were 19.3%, 13.1% had social bookmarks, 0.9% had expert recommendations, and online news outlets picked up eight articles. Significantly higher citation rates were associated with mention in social media, expert recommendation, social bookmarking, and for articles identified as meta-analyses, multicenter studies, randomized controlled trials, and reviews (all P<0.001). The odds of an article being highly cited were significantly increased by a mention in social media (odds ratio, 2.58; P<0.001). Qualitative analysis suggests that article topics discussed on social media are more likely to relate to the more controversial and emotive areas of transplantation. Social media and online attention act as early predictors of the impact of transplant research as measured by later citation rate. Blogging and expert recommendation, in particular, are associated with higher citation rates.