This study reports on the first systematic review focused on lung transplant recipients (LTRs) and provides evidence regarding 1) prevalence of nonadherence to the post-transplant medical regimen; 2) risk factors for nonadherence; 3) impact of adherence-promoting interventions; and 4) transplant-related clinical outcomes of nonadherence in LTRs. Following the PRISMA guidelines, a literature search of 5 databases was conducted, yielding 30 relevant articles. Findings suggested that nonadherence rates varied greatly across regimen components and were not consistently associated with any single risk factor. Effect sizes in terms of correlation coefficients for adherence-promoting interventions ranged from .05 to .45. Mortality rates did not significantly differ by adherence levels. Major limitations across studies were weak methodologies for measuring nonadherence and small sample sizes. This review underscores the need for more rigorous and extensive studies of risk factors and clinical outcomes of nonadherence and for large-scaled theory-based trials to examine adherence-promoting interventions in LTRs.