With energy restrictions, power blackouts and the increase in the cost of oil, other fuels and electricity, illumination in museums has become a serious problem. The author advocates a reexamination of the dependence on mechanical systems to the exclusion of natural light. Although aware of the importance of controlling environmental conditions within museums, he points out the disadvantages of artificial lighting which produces heat and causes damage to sensitive colors and materials. He describes museum buildings, ancient and contemporary, in which natural lighting has been successfully used, supplemented by artificial lighting when needed. Since the era of abundance of low cost energy is over, it behooves architects and museum administrators to reexamine current museum design and exhibition methods. -- AATA