Ziziphus spina-christi is a medicinal plant with many traditional uses. Separation, identification and quantification of the constituents of the plant are of great interest. Phenolic compounds are present in such plants. The present study describes isolation, qualification and determination of some of these phenolic acids using reversed phase HPLC after the purification of the compounds by passing the plant extract through sephadex LH-20 column. pCoumaric acid, rutin, apigenin, quercetin, chlorogenic acid and syringic acid were found and isolated in the methanolic extract of the stem, in which rutin content was found at higher concentration (325.0 mg /100g) and apigenin (122.90 mg/100g). Ferulic acid, rutin, p-hydroxybenzoic acid and chlorogenic acid were found and isolated in the extracts of fruit of Ziziphus with maximum rutin content (15.88 mg/100 g). It seems that the phenolic acid contents in stem are higher than that in fruits.