This paper analyzes monthly data on US international trade prices between 1997 and 1999 in order to investigate the impact of tax influences on intrafirm trade prices. Results indicate that there is substantial evidence of tax-motivated transfer pricing in US intrafirm trade prices. There is a strong and statistically significant relationship between countries’ tax rates and the prices of intrafirm transactions. Controlling for other variables that affect trade prices, as country tax rates are lower, US intrafirm export prices are lower, and US intrafirm import prices are higher. This finding is consistent with theoretical predictions regarding tax-motivated income shifting behavior.