Regression parameters for the length of several bony structures against fish body length, and for body length against body weight, were determined for Owens tui chub Siphateles bicolor snyderi, Lahontan tui chub Siphateles bicolor obesa, and hybrid swarm deriving from the two species. Two-hundred eleven individuals from 16 localities from the Owens River and neighboring basins along the border between California and Nevada were used for regression analyses. The coefficient of determination of linear regressions for scales, pharyngeal arches, dentaries, cleithra, and opercula against body length were consistently high (r(2) >= 0.9). Differences between subspecies were mainly with reference to the intercept parameter in comparisons involving Lahontan tui chub. Coefficients of determination from log-linear length-weight regressions were also high (r(2) >= 0.9) for individual taxa and for the pooled data set combining both Lahontan and hybrid species. The length-weight relationship did not differ between subspecies. Estimates of the length-weight relationship using data pooling both Lahontan and hybrid tui chub suggest a weak allometric growth effect (P < 0.05). The bone-length to body-length and body-length to body-weight relationships presented here will be useful tools for future dietary studies of tui chub predators as well as for archaeological and paleontological studies on tui chub remains.