GABA regulation of secondary metabolic and defense activities has not been reported under stripe rust in wheat. Phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), peroxidases (POX), polyphenol oxidases (PPO), beta glucanase (GLU), and chitinase (CHI) and phenolics, flavonoids, lignin, redox state of glutathione were estimated from leaves and roots at 1, 2 and 4 d of GABA, Puccinia striiformis f. sp. tritici (Pst), GABA + Pst given to 30-d-old seedlings wheat cultivars PBW725 (resistant) and HD2967 (susceptible). Results found deficiencies for phenolics, flavonoids, lignin roots while POX/PPO in leaves at 4 d of Pst in HD2967 but improved under GABA + Pst. Progressive increase of redox of glutathione in leaves and roots was seen in PBW725 while HD2967 improved under GABA + Pst. Increase of PAL/ was gradual over stress time in PBW725 compared to HD2967. Early accumulation of lignin was seen in the leaves PBW725 while HD2967 improved under GABA + Pst. HD2967 increased CHI/GLU significantly during the late stages Individually GABA increased secondary metabolic, and defense activities in both cultivars. Results showed that secondmetabolic and defense over time be for resistance rust. GABA