[en] Theoretical uvby indices are computed from hydrogen-line-blanketed model atmospheres as functions of theta/sub e/ and log g for 0.40 equal to or less than theta/sub e/ equal to or less than 0.70, and 2.0 equal to or less than log g equal to or less than 4.0. Values of theta/sub e/, log g, and y/sub bol/ are derived for 19 blue horizontal-branch stars in the globular cluster NGC, 6397 and the masses of the stars are computed. At least three possible conclusions can be drawn from this analysis: (1) a mass dispersion of 0.5 M/sub mass/ exists on the blue horizontal-branches of some globular clusters, (2) nonstellar contributions to the uvby indices are masking the true stellar indices of some blue horizontal-branch stars, and (3) the emergent flux of some blue horizontal-branch stars is influenced by some stellar parameter whose effect on the uvby indices has not been considered or has been underestimated. (U.S.)