Sirenomelia sequence is a rare congenital anomaly. This is also known as "mermaid syndrome" because of typical feature of lower limb. Sirenomelia sequence is characterized with a single midline lower limb. Our case was an infant delivered at 34 gestational weeks by spontaneous vaginal delivery from a 34 years old gravida 2, para 0. Parents are not relative. Infant has one femur, one tibia and one phalanx at lower extremity. Calcaneus, metatarsals and other bones of the foot are absent. Patient has anal atresia and renal agenesy. Determination of sex was impossible since external genitalia was absent. Although some risk factors (e. g. maternal diabetes) have been suggested, etiolgy of sirenomelia sequence is debated. In this report, we describe a premature infant with sirenomelia sequence because of very rare presentation.