Organically labeled vegetables are considered by many consumers to be healthier than non-organic or 'conventional' varieties. However, whether the organic-labeled vegetables contain more nutrients is not clear. The purpose of this study is to examine the nutritional quality of broccoli using vitamin C, a fragile and abundant nutrient, in broccoli as a biomarker. The vitamin C content was assayed (2,6-dichlorophenolindophenol method) in broccoli samples obtained from supermarkets that are considered the point of consumer consumption. These samples were obtained during different seasons when the broccoli could be either harvested locally or shipped far distances. The findings indicate that vitamin C could be used as a marker under a controlled laboratory environment with some limitations and, although the vitamin C content of organically and conventionally labeled broccoli was not significantly different, significant seasonal changes have been observed. The fall values for vitamin C were almost twice as high as those for spring for both varieties (P=0.021 for organic and P=0.012 for conventional). The seasonal changes in vitamin C content are larger than the differences between organically labeled and conventionally grown broccoli.