A case of large cell undifferentiated carcinoma of the lung metastatic to the placenta and a review of the literature are presented. This is the 44th documented case of placental and/or fetal metastasis from maternal cancer in the past 113 years. Fifty percent of these cases are either malignant melanomas or hematopoietic malignancies. Evidence indicates that these 2 malignancies are more likely to metastasize to the products of conception than are other malignancies.