The country's first-half GDP reached 29.429 billion levs ($21.2 billion/14.8 billion euro), calculated in current prices, NSI said in a statement.
The Bulgarian economy grew by 7.1% in the second quarter, compared to 7.0% in the first quarter and to 7.3% in the second quarter of 2007.
In 2007, the country's GDP grew by 6.2% in real terms, a bit slower than the 6.3% rise in 2006.
Bulgarian government officials have said they expect the country's economy to continue to grow at an annual rate of above 6.0% over the next few years. The government sees the country's economy rising by a real 6.2%-6.5% for the whole of 2008.
(1 euro = 1.95583 Bulgarian levs)