Two health-care firms got a green light to merge.

American Hospital Supply said its proposed merger with Hospital Corp. of America has been cleared by the antitrust division of the Justice Department. American and HCA reached a definitive agreement March 31 for a merger that would create the largest health-care company in the nation. But the proposal still must be approved by the stockholders of both companies and could be thwarted by a competing offer from Baxter Travenol Laboratories. The merger between American and HCA would be worth about $35 a share for American’s stockholders.