The phenol-croton oil peel is one of the most effective procedures for deep skin rejuvenation, with lasting impact on static wrinkles, severe photoaging, scarring, and field cancerization. This chapter revisits its trajectory, from the earliest empirical reports in beauty salons and non-medical clinics in the 1920s to 1950s, to its formal incorporation into medical practice by pioneering surgeons such as Adolph Brown, Clyde Litton, Ed Truppman and Thomas Baker. The publication of the Baker-Gordon formula in 1961 marked a historic milestone, establishing the technique as the gold standard for decades. From 1970 onwards, experimental studies by Spira, Behin, Stegman, and Kligman demonstrated the decisive role of croton oil, occlusion, and friction in determining the depth of dermal necrosis and collagen remodeling. In the 2000s, Gregory Hetter refined the procedure by introducing standardization of concentrations and customization for different anatomical areas, which enhanced predictability and safety. Currently, the phenol-croton oil peel remains superior to many modern technologies, but requires technical rigor, appropriate preparation, and careful attention to the systemic toxicity of phenol. Its history illustrates the transition from empiricism to science, reinforcing the importance of ethics and regulation in the use of deep ablative procedures.