Abstract Previous investigators have shown that P. menziesii has a haploid chromosome number of 13, and both P. macrocarpa and P. wilsoniana have haploid numbers of 12. This study shows that each of the other three species, P. japonica , P. sinensis , and P. forrestii , has 12 haploid chromosomes, indicating that the basic number of chromosomes in the genus Pseudotsuga is 12. This adds to the evidence that P. menziesii with an n-number of 13 arose from a species with 12. Intraspecific hybridization would be a more fruitful approach to a breeding program for P. menziesii than would interspecific crossing. Forest Sci. 18:66-69.