This study analyzes the possible occurrence of plagiarism and self-plagiarism in a sample of articles published in the Scientific Periodicals Electronic Library (SPELL), an open database that indexes business journals in Brazil. The author compared one sample obtained in 2013 (n = 47 articles) and another selected from 2018 (n = 118 articles). In both samples, we verified the guidelines that each of the journals provided to authors regarding plagiarism and the adoption of software to detect textual similarities. In the analysis conducted in 2013, it was found that only one journal (2%) mentioned the word "plagiarism" in its policies, although the majority of the directives required guarantees that no type of violation of authors' rights was contained in the manuscript. In the analysis conducted in 2013, it was determined that there were literal reproductions in 31 published articles (65.9%), and no relevant similarities with other publications were encountered in 16 articles (34.1%). In the 2018 analysis, 69 of the publications (58%) included observations and guidelines related to plagiarism and self-plagiarism. In the analysis conducted in 2018, it was found that similarities (plagiarism and self-plagiarism) occurred in 52 articles (44%), and no relevant evidence of plagiarism or self-plagiarism was found in 66 (56%) manuscripts. Although a reduction in the index of the occurrence of plagiarism was observed, as was an increase in the instructions on the prevention of plagiarism by authors, practices directed at guiding authors by means of directives concerning the importance of preventing plagiarism in manuscripts submitted for publication can be recommended.