Background <p>Idiopathic pulmonary fibrosis (IPF) is more common in older patients, and malnutrition is also frequently detected in IPF patients.</p> Aims <p>We aimed to use the Geriatric Nutritional Risk Index (GNRI) to evaluate the risk of malnutrition and investigate the relationships between malnutrition risk, the frequency of IPF exacerbations, and the risk of mortality in this patient group.</p> Methods <p>In this retrospective study, we evaluated consecutive IPF patients who initiated antifibrotic therapy at our hospital between January 1, 2017 and January 1, 2023, and were 65 years or older. Patients classified the GNRI stage as ‘at risk’ (&lt; 98 points) or ‘not at risk’ (≥ 98 points) based on their GNR scores. The two groups were compared in terms of acute exacerbation (AE), hospitalization, and mortality.</p> Results <p>Our study determined that 41% of patients had malnutrition-related risk at the time of diagnosis. The number of IPF exacerbations was significantly higher in the group at high risk of malnutrition compared to the group without malnutrition risk (2.42 ± 3.42 vs. 0.91 ± 1.67, <i>p</i> = 0.031). Additionally, during treatment, mortality rates were also significantly higher in the group at high risk of malnutrition (50.0%) compared to the group without malnutrition risk (20.6%) (<i>p</i> = 0.025).</p> Conclusions <p>The present study demonstrated that malnutrition-related risk was significantly associated with increased IPF exacerbations. Importantly, these results suggest that the assessment of malnutrition-related risk by GNRI provides information for predicting AE and mortality risk in patients with IPF.</p>