Objective: The aim of our study was to examine the factors associated with mortality in patients who underwent percutaneous endoscopic gastrostomy (PEG) and identify biomarkers that may guide clinical practice. Methods: This retrospective observational study included adults who underwent PEG placement in our center. Demographic data, date of PEG placement, inpatient ward, PEG indication, time from admission to PEG placement, post-PEG complications, and outcome (discharge/mortality) were recorded. Logistic regression analysis was performed to identify factors associated with 90-day and 6-month mortality. Results: Of 100 patients included in the study, 52% were men and the median age was 73 years. The most common indication for PEG was malignancy (n=25, 25%). The most common minor complication was minor peristomal bleeding and peristomal infection requiring tube removal The most common major complication was aspiration pneumonia. Thirty-eight patients (38.0%) died within 90 days and 52 patients (52.0%) died within 6 months of PEG placement. The odds of 90-day mortality were 57.5% lower per 1-unit increase in total serum protein level (odds ratio [OR]: 0.425, 95% CI: 0.230–0.888; p=0.021), 1.6% higher per 1-unit increase in serum CRP (OR: 1.016, 95% CI: 1.006–1.027; p=0.003), and 13.6 times higher in patients with aspiration pneumonia (OR: 13.631, 95% CI: 2.997–61.988; p=0.001). For 6-month mortality, a 1-unit increase in serum albumin level was associated with 81.4% lower odds (OR: 0.186, 95% CI; 0.081–0.430; p<0.001) and aspiration pneumonia with 22 times higher odds (OR: 21.984, 95% CI: 2.412–200.342; p=0.006). Conclusion: Aspiration pneumonia, low total serum protein and albumin levels, and high CRP level were associated with higher mortality.