The firm is a distributor between businesses and it saw sales rise 10.6% in the three months, compared to the same period a year ago.
Operating income, as a percentage of net sales, improved to 21.2% in the second quarter of 2017 from 20.6% in the second quarter of 2016, the group added.
Net earnings for the three months to end June were US$148.9mln, up 13.2% compared to the second quarter of 2016.
"Our diluted net earnings per share were $0.52 during the second quarter of 2017 compared to $0.45 during the second quarter of 2016."
"The second quarter of 2017 felt more like Fastenal," said Dan Florness, president and chief executive.
"We have grown well over the last year, but market headwinds have masked this growth. We continue to ask our customers to challenge Fastenal to be their supply chain partner; their response shines through in the success we are seeing with all of our growth drivers."