Spondylo-epiphyseal dysplasia tarda is an hereditary disease of bone first described by Maroteaux in 1957. The disease affects only boys, then is transmitted on X-linked recessive pattern. The authors describe two tunisians families with 8 patients presenting clinical and radiologic symptoms resembling spondylo-epiphyseal dysplasia tarda but affecting both sexes. Autosomal recessive inheritance is probable in these families. Conclusion is that genetic heterogeneity of the disease must be precise.