The results have come just few weeks ahead of its expected initial public offering.
Facebook has posted a net income of $205 million in the January-March quarter of 2012 compared to $233 million in the year-ago period, the company said in a regulatory filing to the US Securities and Exchange Commission.
The social networking site attributed decline in quarterly profit mainly due to rise in expenses on research, marketing and promotional works.
Facebook's revenue climbed to $1.05 billion in the three months ended March 31, 2012 from $731 million in the year-ago period.
The company said it has 901 million monthly active users as of March 31, an increase of 33 per cent from the year-ago period.
The number of people using its mobile applications each month stood at 488 million at
the end of the quarter.
Facebook said users in Brazil, India and the US were important sources of growth both on its' website and on mobile devices.
"We had 45 million MAUs in Brazil as of March 31, 2012, an increase of 180 per cent from the same period in the prior year, and we had 51 million MAUs in India, an increase of 107
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