Athletes and researchers could benefit from a simple and universally accepted technique to determine whether humans are well-hydrated, euhydrated, or hypohydrated. Two laboratory studies (A, B) and one field study (C) were conducted to determine if urine color (${\text{U}}^{\text{col}}$) indicates hydration status accurately and to clarify the interchangeability of ${\text{U}}_{\mathrm{col}}$, urine osmolality (${\text{U}}^{\text{osm}}$), and urine specific gravity (${\text{U}}^{\text{sg}}$) in research. ${\text{U}}_{\mathrm{col}}$, ${\text{U}}_{\mathrm{osm}}$, and ${\text{U}}_{\mathrm{sg}}$ were not significantly correlated with plasma osmolality, plasma sodium, or hemato-crit. This suggested that these hematologic measurements are not as sensitive to mild hypohydration (between days) as the selected urinary indices are. When the data from A, B, and C were combined, ${\text{U}}_{\mathrm{col}}$ was strongly correlated with ${\text{U}}_{\mathrm{hg}}$ and U„_sm. It was concluded that (a) ${\text{U}}_{\mathrm{col}}$ may be used in athletic/industrial settings or field studies, where close estimates of ${\text{U}}_{\mathrm{sg}}$ or ${\text{U}}_{\mathrm{osm}}$ are acceptable, but should not be utilized in laboratories where greater precision and accuracy are required, and (b) ${\text{U}}_{\mathrm{osm}}$ and ${\text{U}}_{\mathrm{sg}}$ may be used interchangeably to determine hydration status.