Purpose: This study contributes to the current body of literature on students' understanding of academic misconduct, plagiarism, forms of plagiarism, the reasons they plagiarize, the sanctions imposed by academics for plagiarizing and the methods to address plagiarism in written assessments within the Faculty of Natural Sciences, University of Guyana, which was investigated in 2021. Design/methodology/approach: The research design was descriptive and grounded in the pragmatism paradigm. The methodology employed was quantitative, consisting of the collection of data through an online, self-administered questionnaire-based survey. Findings: The results showed that despite students having a conceptual understanding of academic misconduct and plagiarism, they intentionally and unintentionally plagiarized their written assessments, mainly because of the assessment workload (64.9%), busy schedule (52.8%), not understanding the assessment (46.3%) and not knowing how to correctly cite sources (44.6%). Prevalent forms of plagiarism committed by students included finding synonyms for the author's language while keeping to the same general structure and meaning of the original work (48%) and neglecting to cite sources, misquote sources or unintentionally paraphrase a source by using similar words, groups of words and/or sentence structure without attribution (42%). Academic sanctions commonly include giving an overall reduced grade, giving a warning and asking the student to redo the plagiarized work. The study showed that students preferred flexible and lenient penalties to address plagiarism and objected to sanctions that may jeopardize their academic progression. Originality/value: An international literature review will demonstrate extensive research on academic misconduct, particularly plagiarism, emphasizing attitudes and perceptions. Despite Artificial Intelligence (AI) technologies and limited software subscriptions, academic misconduct in Guyana is still poorly understood. Therefore, this study adds to the literature by evaluating tertiary education students' perceptions of plagiarism, given the growing concerns and negative repercussions of plagiarism and student use of AI to produce assignments at this university.