This paper explores the implications of the Vietnam War on human capital. Generally, the term 'investment in human capital' refers to 'Activities that influence future monetary and psychic income by increasing the resources in people' [1, p. 1]. The activity of war represents the profound disinvestment or waste of human capital resulting not only in the personal and social cost of civilian and military casualties, but also in the foregone human investments such as health, education, training, and rational geographic mobility. The costs in terms of the human resources of the civilian economies are especially severe when the fighting takes place within the country. The creation of casualties and refugees, who are wrenched from their economic and social environment, and the redirected priorities of a nation at war have major and long-run implications for the welfare and productive capacity of its citizens. Discussions of the cost of the Vietnam War have tended to underemphasize human capital considerations. Yet, the theory of human capital has been applied widely, as for example in estimating the costs of illness or injury.1 In 1931, J. Clark estimated the cost of death and disability resulting from the First World War [2]. More recently, Professor Robert Eisner, in preparing an estimate of the 'Total costs' of the Vietnam War to the U.S., included items pertaining to 'Cost of the dead' and 'Cost of the wounded' [3]. Some persons may find it offensive to examine some of the implications of war in terms of the theory of human capital. This is a justifiable position. However, we should point out that the crucial aspect of this approach involves the treatment of time, and there is the explicit recognition that income should be broadly interpreted to include psychic aspects which may be exceedingly difficult, if not impossible, to measure. Moreover, our discussion is meant to be suggestive and makes no pretence as to completeness. The economic implications of military casualties are discussed in section 2. A quantitative estimate of the loss of human capital from this cause is calculated for the US economy. The analysis is focused on US military casualities because of the availability of information. In section 3, the economic implications of civilian casualties and refugees in South Vietnam are explored. Again, we recognize that these problems exist on a large scale in North Vietnam and elsewhere in Indochina; however, limitations of time and of information precluded such a broad study. Also, due to limitations of information and of knowledge, no attempt is made to arrive at a quantitative summary estimate of the loss of the human capital of South Vietnam.