A 300 base pair deletion near the 3'-end of the gene encoding Type II (cartilage) collagen has been implicated in the pathogenesis of perinatal lethal osteogenesis imperfecta. We have found similar deletions occurring at a high frequency in normal Asian Indian and West Indian populations generated by a length polymorphism just beyond the 3'-end of the gene. We suggest that this polymorphism provides an alternative explanation of the original results.