Introduction: During the past decade, the molecular mechanisms in the process of tumor metastases and angiogenesis have become better understood. Discussion: The development of metastases requires complex molecular interactions in the detachment of tumor cells from solid tumors, the degradation of the extracellular matrix, escape from apoptosis, locomotion in the extracellular matrix, immunologic escape in the circulation, adhesion to endothelial cells, and extravasation from the circulation at the target site of metastasis and induction of angiogenesis Conclusion: The increasing knowledge of these complex mechanisms offers new therapeutic approaches in the treatment of malignant diseases. This article will give an overview of the molecular mechanisms involved in the development of metastases and angiogenesis, and their clinical implications.