Cervical thoracic duct cysts occur infrequently but are an important consideration when evaluating cystic supraclavicular masses. Only 22 cases have been reported to date. We review the clinical presentation, evaluation, and treatment of 2 cases of large thoracic duct cysts treated with surgical resection. A high suspicion of thoracic duct cyst based on location, radiographic findings, and fine-needle aspiration results is sufficient evidence for recommendation of surgical excision. However, enlarged cysts, as noted in our cases, can obliterate or attenuate the thoracic duct, making it difficult to identify intraoperatively. A high suspicion of thoracic duct cyst is important for identifying and ligating the duct to prevent complications such as chyle leak or chylothorax.