During the period of cold war, NATO alliance was producing defence commodity to protect its members from the common threat of ex-Soviet Union. The paper examines the problem of burden sharing among NATO allies. It is shown that larger countries are benefited more than smaller countries from the production of the public good i.e defence, if the income elasticity of marginal utility of income is greater than one in absolute value. Complete demand systems are employed for estimating the income elasticity of marginal utility of income.