Rainbow trays are human-factor engineered anesthetic drug trays incorporating the ISO26825 critical-care colours into a compartmentalized tray system that segregates drugs by type to reduce medication error. Anesthetists routinely choose, prepare, administer, and record several potent intravenous drugs in relatively short periods, alone and sometimes while stressed or fatigued. The Rainbow Trays standardized system segregates syringes aligned to critical-care label colours, reducing cognitive load and improving efficiency. Rainbow trays have shown to change behavior and increase awareness of drug safety during administration supporting best practice and patient safety. Rainbow Trays effectively ‘make it easier to get it right’.