This paper conducts a comparative analysis of the productive efficiency of foreign-owned and US-owned multinational commercial banks operating in the US. A multiproduct translog stochastic-cost frontier model approach is used to estimate cost inefficiency scores. Ordinary Least Squares and Tobit regressions are used to identify the key factors associated with inefficiency. The results indicate that foreign-owned multinational banks operating in the US are significantly less efficient than their US-owned counterparts and that large multinational banks in holding company networks carrying fewer foreign assets tend to be more efficient.