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Studies have suggested the importance of polyphenolic compounds as antioxidants and in prevention of degenerative diseases. Vineyard cultural practices that improve polyphenolic content of wine can be desirable. The effects of three cluster thinning or fruit removal treatments on anthocyanins, total phenolics, antioxidants, and resveratrol content of ‘Chambourcin’ wines were investigated. Anthocyanin levels, total phenolic and antioxidant capacities of wines were measured spectrophotometrically after incubation with specific reagents. Levels of trans-, cis-resveratrol and their glycosides in wine samples were analyzed by direct injection into HPLC coupled with photodiodearray detection. Cluster thinning increased the polyphenolic composition of wines as indicated by increases in anthocyanins, total phenolics, antioxidants and total resveratrol content. Strong positive correlation (r=0.97) was found between total phenolic content and antioxidant capacity indicating the importance of total phenolics in affecting antioxidant capacity. It was concluded that cluster thinning produced ‘Chambourcin’ wines with increased potential health benefits.