Dementia is a rising public health concern. Feeding and nutritional problems increase as the disease progresses, affecting clinical course and caregiver burden. While some guidelines advise against percutaneous endoscopic gastrostomy (PEG) and tube feeding in advanced dementia, conflicting evidence exists. This study aims evaluating nutritional status and the influence of PEG-feeding on outcome and evolution of nutritional/progonosis markers of patients with severe dementia (PWSD) who underwent gastrostomy for nutritional support. We conducted a 16-year rectrospective study on 100 PEG-fed PWSD with strong familiar support. We evaluated survival PEG-feeding period, safety, and objective nutritional/progonosis data at the gastrostomy day and after 3 months: Body Mass Index (BMI), Mid Upper Arm Circumference, Tricipital Skinfold, Mid-Arm Muscle Circumference, albumin, transferrin, total cholesterol and hemoglobin. Most patients presented low values in these nutritional/progonosis parameters. No major life-threatening PEG complications were reported. The mean survival time after gastrostomy was 27.9 months (median of 17 months). Female sex, BMI recovery at 3 months, and higher baseline hemoglobin levels were associated with a reduced risk of death and increased survival time. The study concluded that, in carefully selected PWSD with strong familiar support, PEG feeding can improve nutritional status and have a positive impact on survival.