Although Poland's syndrome is classically considered to consist of simple syndactyly, limb hypoplasia, and ipsilateral pectoral muscle agenesis, a rate group of patients with pectoral agenesis has more severe limb deficiencies. In ten of these patients and in similar patients reported in the literature, a broad range of limb deformities was observed. The authors classified the patients according to limb anomalies: type 1, five digits present even if hypoplastic; type 2, functional border digits with the absence of central digits; type 3, more severe absence deformities with no functional digits; and type 4, radial ray defects with absent thumb. The understanding that Poland's syndrome includes a spectrum of limb anomalies is important in searching for associated birth defects, in genetic counseling, and, possibly, in elucidating the pathogenesis of the syndrome.