A 1961-2000 review with 35 refs. covering flame retardants, smoke suppressants, and the effect of various modifiers on other properties of UP Flame retardants and smoke suppressants are grouped separately by reason of their different mechanisms of action. Organochlorine compounds, hydrated organic fillers, phosphorus-based, and halogen-free flame retardants are reviewed. The halogen-free modifiers are environment-friendly and are preferred in recent research trends.