Samsung, the world's largest maker of memory chips and flat-screen televisions, forecast sales of 37 trillion won in January-March.
It released its earnings guidance, which does not include a net profit estimate, before official first-quarter results later this month.
The estimated operating profit represents a 34 percent fall from the figure in the first quarter of 2010. The guidance did not elaborate on the performance of each division, but analysts said the figure probably reflects weakness in the flat panel and television sectors.
In the fourth quarter of last year, the company reported an operating profit of 3.01 trillion won on sales of 41.87 trillion.
Analysts cited by Dow Jones Newswires said Samsung's earnings likely bottomed out in the first quarter and would rise throughout the year.
They said the upcoming release of a new smartphone and an upgraded version of its tablet computer, as well as components used for those products, were expected to boost sales.
New TV models were also expected to swell revenue in the second quarter.