The Democratic Congressional Campaign Committee raised $6.48 million in April and ended last month with $25 million in cash on hand.
The DCCC has posted big fundraising figures in recent months, often outraising its counterpart, the National Republican Congressional Committee.
A DCCC spokesman said this was their "best April in history."
By comparison, the DCCC raised just less than $3 million in April of 2006, a year in which they took control of the House, according to Federal Election Commission filings.
The NRCC has not yet released its monthly fundraising numbers, which are due to be filed at the FEC on or before Sunday.
Democrats have an uphill climb to net the 25 seats needed to take back the chamber, which they lost in 2010. The first salvo in that effort will come next month in the Arizona special election to replace former Rep. Gabrielle Giffords (D). Both parties and their allies are spending heavily on the swing seat.