The A11 southbound near Barton Mills was blocked following a two-vehicle crash.
It happened at about 11.52am and involved a Mitsubishi and a Vauxhall, but it is not yet known if anyone has suffered any injuries.
A spokeswoman for Suffolk police said just one of the lanes was blocked so traffic could get through.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here