Less developed countries have received substantial foreign aid in transport infrastructure, making its quantitative assessment important. This paper employs the first comprehensive census on all the business establishments in Cambodia for 2011 and examines the effect of aid in road infrastructure on the location of foreign and domestic firms. Estimating a negative binomial model, we find that aid disbursements in roads have little influence on the number of foreign firms across communes. While aid has a significantly positive effect on that of domestic firms, its economic impact is relatively smaller than other determinants such as population size, electricity access, and labor supply. Thus, there appears to be a limited impact of aid in roads on the location of economic activity in Cambodia.