Interest in the health benefits of vegetables prompted an investigation of the levels of carotenoids in commercial varieties and UA breeding lines of spinach. Plant carotenoids perform a critical function as antioxidants, providing protection against a variety of reactive oxygen species generated primarily during photosynthesis. When ingested by humans, these compounds maintain their antioxidant activities and are receiving considerable attention in relation to multiple health benefits, including cancer prevention. While the best-known and most-studied carotenoid is beta-carotene, other carotenoids are now receiving attention due to their higher antioxidant activity compared to beta-carotene. Most dark-green leafy vegetables, such as spinach and kale, are relatively high in carotenoids, especially lutein. In this study, significant differences in average content of both lutein and beta-carotene were found between genetic lines of spinach. Some lines exhibited considerable variation between plants, while others were highly uniform. There was a very high correlation ( r 2 = 0.96) between lutein content and betacarotene content. The significant difference between spinach lines suggests that improvement of general carotenoid antioxidants and lutein could be obtained through a breeding program.