Athletes in weight category sports frequently practice short-term weight loss to make weight, which often involves manipulating total body water. In Eastern medicine and phytotherapy, dandelion has long been considered to have a diuretic effect, yet empirical investigations of this effect are scarce. This study investigated whether the ingestion of a commercially available dandelion root powder with a large bolus of water acutely elicited a diuretic effect beyond the effect on urine output elicited by the bolus of water alone. In an open-label counterbalanced, crossover design with two separate laboratory visits, physically active young adults (n = 14; M/F, 12/2; age, 25.5 ± 4.7 years) ingested 1 L of still water with (DAND) or without (CON) four capsules providing a total of ∼2.1 g of a commercially available dandelion root powder. The primary outcome was cumulative urine output over the 4 hr following ingestion. Cumulative urine output was 1,164 ± 244 g in CON and 1,268 ± 213 g in DAND, with the mean difference (95% confidence interval) of 105 (−35 to 244) g (p = .13; g = 0.45). Under the experimental protocol employed, the commercially available form of dandelion ingested, the dosing strategy used, and the cohort investigated, cumulative urine output was similar regardless of whether dandelion root powder was co-ingested with a large bolus of water. These results indicate a lack of support for the purported diuretic effect of dandelion. Future studies should investigate different time courses, dosing strategies, and sources of dandelion, as well as study designs with greater ecological validity for weight category sports, before definitive conclusions can be made.