Recombination rates in humans tend to be sex specific. For a given map interval delimited by genetic markers, the difference between male and female recombination rates may be measured by the ratio, R, of female-to-male map distance. On average over all chromosomes, R is close to 2, but this ratio is region specific. The spatial variation of R can be captured by a low-order (linear, quadratic, etc.) trend across the length of the chromosome. Chromosome maps have been constructed that take into account such trends. Resulting map distances tend to be more accurate than when such trends are ignored. These maps may be obtained at URL ftp://linkage.rockefeller.edu/SexSpecMaps/.