The brewer's net income fell to $82.9 million, or 44 cents per share, in the quarter that ended March 26. That was in line with analyst' expectations but down from $104.6 million, or 56 cents per share, last year.
The Denver-based brewer's revenue excluding excise taxes rose 4 percent to $690.4 million, just missing analysts' expectations of $690.5 million.
Molson's shares fell $2.37, or 4.9 percent, to $46.03 in premarket trading.
But the brewer's total worldwide beer volume fell 1.5 percent over the previous year. The company said that last year's first quarter benefited from an early Easter and the Vancouver Olympics. The U.S., United Kingdom and Canada are Molson Coors' main markets.
Molson was helped by MillerCoors, the joint venture with SABMiller plc that sells both companies' brands in the U.S.
MillerCoors' revenue was virtually flat, but it increased net income by about 12 percent by cutting costs and through its "mind the gap" campaign. That has trimmed the price difference between low-end and high-end beers to persuade customers to trade up to higher-priced brands like Blue Moon and Leinenkugel.
(Copyright 2011 by The Associated Press. All Rights Reserved.)