Technical Abstract: Phenolic and other compounds were extracted from micropropagated axillary shoots (microshoots) of the walnut (Juglans regia L.) cultivars ‘Chandler’, ‘Howard’, ‘Kerman’, ‘Sunland’, and ‘Z63’. Among cultivars, microshoots showed differences in phenolic compounds, phenolic acids, flavonoids and proanthocyanidin. All cultivars contained the phenolics acids chlorogenic acid, gallic acid, and p-coumaric acid; the naphthoquinone juglone; and the flavonoid quercetin. Flavone was not detected in any cultivars and the phenolics acids syringic acid and vanillin were present only in microshoots of ‘Howard’. Microshoot extracts had different antioxidant activity with ‘Kerman’ the highest and ‘Chandler’ the lowest in each of three antioxidant assays: the phosphomolybdenum assay (PPM), reducing power assay, and 2,2-diphenyl-1-picrylhydrazyl (DPPH)-scavenging effect. There was a strong linear relationship between total phenolic compound content of microshoots and increasing antioxidant activity.