Remarkable progress has been made in the treatment of osteosarcoma in the past two decades as a result of the development of effective adjuvant chemotherapy. However, the prognosis is poor in patients with early lung metastases. We review the lactate dehydrogenase release prognostic factor in the development of early lung metastases. This is a retrospective study. Eighteen patients with osteosarcoma were divided in two groups: Group A, patients with normal lactate dehydrogenase and Group B, patients with elevated lactate dehydrogenase. A univaried analysis was established. Ten patients (55%) had elevated levels of lactate dehydrogenase at diagnosis; nine of these patients developed lung metastases in the first twelve months. The difference in patients with normal levels of lactate dehydrogenase was significant (p: 0.02). The value of lactate dehydrogenase as an isolated single factor is limited. It is necessary to consider the tumoral volume, the patient's age and the histologic subtype in the prognosis of these patients, to predict the early development of pulmonary metastatic disease.