Orientation: Leadership styles influence knowledge workers’ job-stress-related presenteeism (JSRP) and, ultimately, organisational performance. Knowledge workers generally work under strict deadlines in fast-paced, stressful environments, and require organisational support.Research purpose: The objective of this study was to examine empirically the effect of three leadership styles, namely transformational, transactional and laissez-faire, on job-relatedstress presenteeism in knowledge workers across a number of industries in South Africa.Motivation for the study: Absenteeism has been the subject of much investigation but more research is required into the antecedents and consequences of presenteeism, the phenomenon of employees being physically present at work, but not fully functional and therefore unproductive. Illness as an antecedent to presenteeism has been studied, but limited attention has been given to presenteeism caused by stress. There are very few studies that investigate leadership styles as antecedents for JSRP and this study therefore sets out to provide quantitative evidence of this relationship.Research design, approach and method: The researchers used a cross-sectional quantitative approach within the positivism research philosophy. Two questionnaires were administered: the multifactor leadership questionnaire form 6S and the job-related-stress presenteeism questionnaire. Descriptive statistics and Pearson’s product-moment correlation were used to answer the research questions. The participants (N = 242) were knowledge workers, representing 12 widely categorised industries. The researchers analysed job role descriptions to ensure the respondents were all knowledge workers.Main findings: Transformational leadership has a higher negative correlation with JSRP than does transactional leadership, whereas laissez-faire leadership has no significant relationship with job stress or JSRP.Practical/managerial implications: The research provides a compelling case for investment into transformational and transactional leadership development by showing the preventative effect that transformational leadership and, to a lesser degree, transactional leadership, has on stress-associated presenteeism.Contribution/value-add: Presenteeism lowers organisational performance even more than absenteeism does, and exists at huge cost to employees’ quality of work-life. This empirical study, the first to use valid, reliable questionnaires to investigate the relationship between transformational, transactional and laissez-faire leadership on the one hand, and JSRP on the other, suggests that transformational leadership development should be prioritised.