De Quervain tenosynovitis (DQT) is a condition that affects the first extensor compartment of the wrist, resulting in stenosing tenosynovitis. This work aimed to evaluate the effects of platelet-rich plasma (PRP) injection in the treatment of DQT in comparison with corticosteroid (CS) injections. This study was carried out on 40 DQT patients aged above 18 years old of both sexes, based on a combination of clinical symptoms and signs including persistent tenderness on the radial styloid, swelling on the radial styloid, positive provocative tests such as the Finkelstein test, and patients with failed medical treatment. Patients were divided into two equal groups: group I and group II.Group I was injected with PRP, and group II was injected with CS. Follow-ups were conducted at two weeks and six months. There were statistically significant differences among both groups regarding the visual analog scale (VAS), and Disabilities of Arm, Shoulder, and Hand (QuickDASH-9) score. However, complications were statistically insignificant between both groups. After injection, CS was better than PRP after two weeks, but PRP was superior to CS after six months concerning QuickDASH-9 and VAS. These differences were statistically significant. CS is more effective than PRP in the short term (two weeks) and PRP is more effective in the intermediate term (six months). Both modalities are safe; however, PRP is relatively safer than CS.