Objectives: To evaluate how age-related trends in nutritional status, physical health, and parental well-being in females with Rett syndrome may be related to gastrostomy placement and to examine the impact of the procedure on mortality. Study design: We included 323 females from the Australian Rett Syndrome Study and analyzed their demographic, genetic, and child and parental health data collected from over 6 waves of follow-up questionnaire between 2000 and 2011. We used mixed-effects models to estimate the association between repeated measures of outcomes and age, gastrostomy placement and their interaction and Cox proportional hazards regression models to estimate relative risks of mortality for individuals with gastrostomy. Results: Nearly one-third (30.3%) of the cases underwent gastrostomy placement. Nutritional status based on weight, height, and body mass index (BMI) improved over time, and BMI was greater in individuals with gastrostomy placement than in those without (adjusted β = 0.87, 95% CI 0.02-1.73). There was no association between gastrostomy placement and individual's physical health outcomes or parental physical and mental health, nor did the age trend of these outcomes vary by gastrostomy insertion status. Nevertheless, among those at risk of suboptimal weight, the all-cause mortality rate was greater in those who had gastrostomy placement compared with those who had not (hazard ratio 4.07, 95% CI 1.96-8.45). Conclusion: Gastrostomy placement was associated with improvement in BMI in females with Rett syndrome, but its long-term impact on individuals and their families is unclear.