Abstract: Well-developed coronary collateral vessels in patients with symptomatic coronary artery disease were shown to be associated with reduced future cardiovascular morbidity and mortality. However, the majority of patients with coronary artery disease lack adequate functional coronary collateral circulation. Stimulation of collateral vessel development by angiogenic growth factor therapy (therapeutic angiogenesis) has been tested in many clinical trials in the past, but the potential of this new treatment paradigm has not been realized yet in late stage clinical trials. Mechanistic insights into collateral vessel development and the collective clinical experience in the past decade identified specific obstacles that might have impeded the progress in the field. This review identifies some of the key conceptual, technical, and clinical hurdles and recommends strategies to overcome them in future clinical trials.