Objectives: To determine whether authors of scientific publications in molecular biology declare patents and other potential financial interests.Design: Survey of a 6-month sample of papers related to molecular biology in Nature.Methods: The esp@cenet worldwide patent search engine was used to search for patents applied for by the authors of scientific papers in Nature that were related to molecular biology and genetics, between January and June 2005.Results: Of the 79 papers considered, four had declared that certain authors had competing financial interests. (...) Seven papers in which no financial interests were declared had authors with patent applications that were based on the research in the paper or were closely related to it. Another paper had two authors with connections to biotechnology companies that were not disclosed.Conclusion: Two thirds of the papers in which authors had patent applications or company affiliations that might be considered to be competing financial interests did not disclose them. Failure to disclose such information may have negative implications on the perception of science in society and on its quality if the possible bias is hidden. Journals should make greater efforts to ensure full disclosure, and scientific institutions should consider failure to disclose financial interests as an example of scientific malpractice. Establishing a register of interests for scientists is one way to increase transparency and openness. (shrink)