Phytochemical analysis of Eschscholzia californica showed that both aerial parts and roots contained alkaloids, the latter being richer than the former, it contained up to 1.6% alkaloids. The alkaloids most commonly reported in Eschscholzia californica included sanguinarine, dihydrosanguinarine chelirubine, macarpine, dihydromacarpine, californidine, chelerythrine, dihydrochelerythrine, chelilutine, dihydrochelilutine, sanguirubine, escholtzine, N-methyllaurotetanine, caryachine, O-methylcaryachine, protopine, allocryptopine, reticuline, methyl laurotetanine, hunnemanine, norsanguinarine, pavine alkaloid (6S,12S-neocaryachine-7-Omethyl ether N-metho salt), 1-(3-hydroxy-4-methoxybenzyl)-2-methyl-6,7-methylenedioxy-1,2,3,4-tetra hydroisoquinoline, as well as the dihydro-intermediates. The plant also contained a variety of colours including orange, red and yellow due to its different carotenoid composition. Six flavonol 3-O-glycosides were isolated from the aerial parts of Eschscholtzia californica. Flavonoids, in the Eschscholzia californica, occurred mainly as quercetin isorhamnetine glycosides. The previous pharmacological studies revealed that the plant possessed antifungal, analgesic, anxiolytic, sedative, behavioural activities and beneficial effect in vasomotor headache with an interesting mechanisms. This review was designed to discuss the chemical constituents and pharmacological effects of Eschscholzia californica. Keywords: Eschscholzia californica, pharmacology, contents, chemicals, therapeutic