The aim of this study is to determine acetic acid, ascorbic acid, citric acid, oxalic acid and tartaric acid in Sudanese medicinal plants (Adansonia digitata fruit pulp, Hibiscus sabdriffa calyx, Hyphaene thebaica fruit pulp and Tamarindus indica pulp) by RP-HPLC-UV method. The method used is based on using an ultrasonic bath for extracting organic acids. The investigation showed that concentrations of ascorbic acid (1.65 mg/g ±0.099), citric acid (56.00 mg/g ±0.22), and oxalic acid (1.35 mg/g ±0.039). The highest values for Adansonia digitata compared to other plants in this study. Tamarindus indica showed higher concentration of tartaric acid (23.75 mg/g ± 0.0.36) compare to other plants, and Hypheane thebaica showed lower concentration of ascorbic acid (0.02 mg/g ±0.242). These Sudanese medicinal plants are recommended as a promising source for the above mentioned organic acids; could contribute considerably towards meeting human nutritional requirements for normal growth and protection against several diseases.