The behavior of asphaltene in live oils was investigated using a fully visual PVT cell equipped with a laser-based particle detection system. Through a series of isothermal pressure depletion experiments, the asphaltene stability envelope was established for several Gulf of Mexico oils. These tests were performed under pressure and temperature conditions typical of a field production system. Evidence of asphaltene precipitation above and redissolution below the saturation pressure was observed. Significantly, these tests also showed that pressure depletion-induced asphaltene precipitation is a highly reversible process. This latter observation helps to resolve a long-running debate in the literature concerning the reversibility of the asphaltene precipitation and flocculation process.