Background: High-abundance plasma proteins are involved in disease-associated pathways and are useful in the diagnosis of nutritional and disease states. However, little is known about how concentrations of many plasma proteins vary between individuals from different ethnocultural groups with different dietary habits. Objective: We explored the association between plasma proteomic groups, dietary patterns, and ethnicity in the Toronto Nutrigenomics and Health Study, an ethnically diverse population of healthy young adults. Design: Concentrations of 54 high-abundance plasma proteins were measured simultaneously by liquid chromatography/multiple-reaction monitoring - mass spectrometry in 1090 individuals. Principal components analysis was used to identify plasma proteomic groups. Linear regression was used to investigate relations between proteomic groups and previously identified dietary patterns (Western, prudent, Eastern). Differences in individual protein concentrations between ethnocultural groups were tested by using general linear models. Results: Four independent principal components representative of proteomic groups were identified. Principal components 1 and 2 included proteins from multiple pathways. Component 3 was inflammatory, and component 4 included coagulation cascade proteins. East Asians and South Asians had lower component 1 scores, and East Asians had higher component 2 scores. South Asians had higher average scores for component 3. Individual protein concentrations also varied across ethnocultural groups. Principal component 1 was positively associated with the Western dietary pattern and inversely associated with the Eastern pattern. Component 3 was positively associated with the Eastern pattern. Conclusions: Plasma proteomic groups differ between young adults of diverse ethnocultural groups with different dietary habits. These differences may partly account for different rates of cardiometabolic disease later in life.