To identify and compare the nutritional composition of different kinds of citrus, three examples (Citrus fruit, Kumquat, and Hallabong) were taken from Jeju island in Korea at the same time and their nutritional compositions were measured using the Association of Official Analytical Chemists (AOAC) method. The proximate components (moisture, protein, fat, fiber, ash, and carbohydrates), mineral and vitamin contents were measured. The Nutrient composition revealed some significant differences among the Citrus. The Citrus fruit has more moisture and Fe content than those of the Kumquat. The Kumquat contained more ash, Ca, Na, Mg, Zn, Vitamin A, and B1 than the other Citrus specimens, while the Hallabong had the most protein and Fe. However, fiber, K, Vitamin B2, C and niacin contents were not significantly different among the specimens. The results demonstrate that the three kinds of citrus used in this study have different nutritional compositions, but they can all be used as a good food for supplementation of K, vitamin A and C. We hope the nutritional analysis of Citrus specimens will be helpful in meeting the consumer's interest in these Citrus, and increase the export of our Citrus produce.