Absence of the right pectoralis major muscle and hypoplasia of the ipsilateral breast was observed in 3 females and hypoplasia or agenesis of the right pectoralis major muscle in 2 males of the same family. One member of this family, a 17-year-old girl, underwent a right latissimus dorsi muscle flap, placement of silicone-gel breast implant, and a right infraclavicular natural Y prosthesis. Although none of our 5 patients from this family had congenital upper limb abnormalities, we believe that they still qualify as having Poland's syndrome. This would distinguish them as being the fourteenth known family reported in the world literature with this diagnosis. A brief review of the history as well as hypotheses of etiological mechanisms are presented.