Starting with the male chiasma distribution for chromosome 2, a significantly better fit is obtained to lod scores for the X chromosome if terminalization of distal chiasmata is assumed. The linkage data are not consistent with a uniform distribution of chiasmata, absence of terminalization, or restriction of terminalization to the distal band. As information about the genetic map of the X chromosome increases, the map will be freed from assumptions about chiasma distribution. At present, however, even fragmentary data on the male are useful to construct a genetic map that, by converting physical assignments to equivalent genetic recombinations, has no inconsistencies between genetic and physical map orders.