Shares fell more than 2 percent before the market open on Tuesday.
For the three months ended March 31, Valero Energy Corp. earned $495 million, or $1.05 per share. A year ago the San Antonio-based company earned $964 million, or $1.87 per share.
Stripping out a tax benefit of 45 cents per share, earnings were 60 cents per share. This was below the 73 cents per share that analysts surveyed by Zacks Investment Research predicted.
Revenue totaled $15.71 billion.