Relationship quality plays a key role in maintaining the connection among parties in a supply chain. Relationship quality promotes loyalty of the supply chain’s factors. This study applies structural equation modeling (SEM) to point out factors affecting the relationship quality and loyalty between farmers and food companies in the rice supply chain. The research data were collected by stratified sampling with a sample size of 232 farmers associating with food companies in the rice supply chain in the Mekong Delta. The four impacting factors that the study has found out include trust, perceived benefit, support policy, and payment terms. Most importantly, the study has demonstrated that relationship quality has a positive correlation with loyalty among parties in the regional rice supply chain.