Family Dollar (FDO) said in a statement that its board rejected the Dollar General bid "on the basis of antitrust regulatory considerations."
The Dollar General (DG) bid, at $78.50 per Family Dollar share, topped the offer from Dollar Tree (DLTR) of $74.50 per share, or about $8.5 billion.
Also, Dollar General offered all cash, as opposed to Dollar Tree's offer combo of cash and stock.
Family Dollar CEO Howard Levine said that the board's decision was unanimous and reaffirmed support for its pending merger with Dollar Tree.
A spokeswomen for Dollar General declined comment. The company's stock dipped on the news.
All three of the chains specialize in low-cost consumer goods.
Dollar General calls itself the largest discount retailer in the U.S., with more than 11,000 stores in 40 states.