The Portsmouth Traffic Circle is a four-point rotary in the city of Portsmouth, New Hampshire.

The southern exit of the circle provides access to Interstate 95 north and south, although only northbound I-95 traffic enters here. The eastern and northern exits are part of the U.S. Route 1 Bypass, and the western exit marks the eastern end of U.S. Route 4, as well as the southern terminus of NH Route 16 and the Spaulding Turnpike. Traffic from southbound I-95 also enters the circle here after navigating a circuitous series of ramps from exit 5.

When it was built, the circle marked the northern terminus of the New Hampshire Turnpike, later designated as part Interstate 95, and linked the NH Turnpike with the Spaulding Turnpike to form what the New Hampshire Department of Transportation's Bureau of Turnpikes collectively terms the "Eastern Turnpike". Although I-95 was extended north in the 1970s, bypassing the circle to cross into Maine over the Piscataqua River Bridge, that segment of I-95 is not part of the Turnpike. NHDOT still considers the NH Turnpike, now known as the Blue Star Turnpike, to end at the circle.

Drivers leaving the circle to join I-95 can head south towards Massachusetts or north to Maine. The circle also provides motorists with a connection to Kittery, Maine, and originally linked the NH Turnpike to the Maine Turnpike, via US 1 Bypass North. The portion of the Bypass south from the circle leads to US 1 and the seacoast region. US 4 travels west toward Concord, while the Spaulding Turnpike and NH 16 link the seacoast with the lakes region and the White Mountains.

According to the NHDOT, the "length" of the traffic circle is .