This pilot study analyzed the impact of retweeting on the frequency of scientific articles from Nature, Science, and PLoS ONE being mentioned on Twitter. When including versus excluding retweets, the top 10 most frequently tweeted articles from Nature and PLoS ONE showed high correlation in frequency rankings. For Science the correlation was lower, indicating retweets may impact frequency rankings more for that journal. The results were only for these specific journals so a larger study across more journals is needed to better understand the potential impact of retweeting on altmetrics.