In recent years, the nursing profession has undergone significant transformations, prompted by evidence such as that presented in the Francis Report (Powell, 2013), which highlighted a gradual erosion in the attention given to the so-called Fundamentals of Care. These activities, historically regarded as the cornerstones of daily nursing practice, have progressively lost their centrality, sometimes becoming associated with processes of professional deskilling (Palese et al., 2019). The term Fundamentals of Care refers to the essential needs of the patient—physical, relational, and psychosocial—and the nursing actions required to meet them (Feo et al., 2018). These interventions not only ensure the comfort and dignity of the patient but also serve as crucial moments for clinical observation and decision-making processes (Kitson, 2018; Palese et al., 2019). Daily hygiene, for example, allows for the monitoring of skin integrity and prevention of pressure ulcers, while oral care may reveal signs of dehydration or infection (Kramer & Splieth, 2022). The omission or delay in delivering such essential care is now encompassed by the phenomenon known as Missed Nursing Care (MNC), defined as “any aspect of required patient care that is omitted, either in part or in whole, or delayed” (Kalisch et al., 2009). This concept originated from a qualitative study conducted by Kalisch et al. (2009), which identified nine core categories of missed care, including patient mobilization, nutritional support, emotional support, personal hygiene, and clinical monitoring. Subsequent research expanded this definition to include caregiver support and patient education at discharge (See et al., 2020). Numerous studies have investigated the determinants and consequences of MNC, identifying key contributing factors such as time constraints, staffing shortages, resource limitations, ineffective work organization, and the increasing complexity of care needs (Currie et al., 2005). Additional evidence suggests that nurses with more experience or higher levels of education report higher frequencies of missed care, possibly due to a different prioritization of nursing tasks (Falk et al., 2023). Furthermore, the care setting appears to be a significant factor, with MNC being more prevalent in medical and surgical units compared to intensive care or maternal-infant care settings (Parise et al., 2021). The literature has increasingly emphasized the link between missed nursing care and patient safety, showing that care omissions are associated with higher rates of adverse events and decreased patient satisfaction (Eileen et al., 2016; Sasso et al., 2019). It has also been demonstrated that organizational safety culture—particularly in aspects such as managerial support and teamwork—directly influences the frequency of MNC (Kim et al., 2018). These findings have been further corroborated by subsequent studies that reveal strong associations between MNC, perceived care quality, and clinical safety. From a health system perspective, patient safety represents a fundamental objective (Evans, 2010), and failure to deliver fundamental nursing care poses a tangible barrier to achieving this goal (Kalisch et al., 2009). Despite growing recognition of missed nursing care (MNC) as a quality indicator, its potential role as a determinant of patient safety outcomes remains underexplored. Clarifying this association is crucial for informing targeted interventions aimed at improving clinical outcomes and minimizing preventable harm. Indeed, care omissions can trigger adverse events, defined as “unexpected incidents related to care processes that result in unintentional and undesirable patient harm” (Cascini et al., 2019). Based on these premises, this study aims to address the following research question: Is there an association between missed fundamental nursing care and the occurrence of adverse events in hospitalized patients? The aim of this systematic review is to examine the association between missed nursing care and adverse events in hospitalized patients, synthesizing current evidence and identifying consistent patterns that can inform future patient safety strategies.