Background: Authorship is increasingly influential in career progression and academic promotion. This study aimed to examine authorship trends in surgical titles between 1998 and 2008, and to compare these trends with those in general medicine publications.Methods: Clinical trials published in high-impact medical and surgical titles were identified. The number of authors associated with these studies and trends over time were analysed using PubReMiner (TM). Trends were then compared between titles with and without author contribution forms (ACFs). Author numbers in top-cited articles were correlated with citation rates.Results: Some 6290 trials involving 54 120 different authorships were identified. A significant difference was found between authorship numbers associated with clinical trials in medicine versus those in surgery (P = 0.003). Introduction of ACFs did not influence the number of authors per trial (P = 0.670). The top 100 most highly cited articles accounted for 114 935 citations; author number correlated with subsequent citation rate (r = 0.26, P = 0.011).Conclusion: Author numbers have increased in the past decade, in both medical and surgical journals. Although medical output is associated with significantly higher levels of authorship, the difference cannot be explained by complexity of research alone.