This study pioneers the application of the New Economics of Labor Migration theory to outline and estimate two opposite effects of labor loss driven by the migration and remittances of adult children on the health of left-behind elderly parents through the changing rural market constraints. We use China's rural household survey data and simultaneous equation econometric techniques to estimate the effects of migration on the physical and mental health of left-behind elders. Results indicate that the loss of labor to migration has a significantly negative effect on the health of left-behind elders, but remittances from migrants can compensate for the adverse effect. This study provides a comprehensive understanding that remittances from migration relax the constraints on household resource allocations in undeveloped rural areas with imperfect market conditions. Overall, left-behind elderly parents benefit from migrant children both physically and mentally. Acknowledgement : Authors gratefully acknowledge the financial support by National Science Foundation of China (Grants: 71673137), Nanjing Agricultural University (Grants: Y0201400037, SKCX2015004), Education department of Jiangsu province (Grant: 2014SJD069), Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), China Center for Food Security Studies at Nanjing Agricultural University, Jiangsu Rural Development and Land Policy Research Institute, and Jiangsu Agriculture Modernization Decision Consulting Center. All remaining errors are ours.