Inventories were up 4.7 percent from March 2012 levels, the bureau said.
Wholesale sales slipped 1.6 percent to $414.7 billion in March, although sales were still up 1.3 percent compared to March 2012, the U.S. Commerce Department agency said.
Sales of durable goods dropped 0.6 percent month to month, though they were up 1.7 percent from March 2012. Sales of non-durable goods dropped 2.5 percent February to March, but rose 1 percent from the same month a year earlier.
The March inventories-to-sales ratio for wholesalers, seasonally adjusted, was 1.21, the bureau said. The March 2012 ratio was 1.17.