The new chemical plants built in the 1950s and 1960s were larger than earlier ones and operated at higher temperatures and pressures. The result was an increase in serious accidents. This led to the more systematic and technical approach to safety, known as loss prevention. Its distinguishing features include the quantification of risk, the identification of hazards by Hazop, audits, inherently safer design, more thorough investigation of incidents, better incident reports and the study in much greater depth than before of explosions, runaway reactions and the dispersion of leaks. New techniques such as Hazop were adopted more quickly than inherently safer design which needs a fundamental change in the design process. Significant papers, both the seminal ones that introduced new ideas and the evangelical ones that spread them, are listed. Finally, the present status of loss prevention is summarized.