At least $200bn (£100bn) worth of counterfeit goods were sold in 2005, an Organisation for Economic Cooperation and Development (OECD) report has said.
Software is one of the most commonly pirated items
But the total value of counterfeit items made and sold worldwide - from medicine to computer software - could be much higher, the OECD added.
It said the products made were "often substandard" and "can even be dangerous".
The OECD called on nations to increase the action taken against the crime.
The $200bn approximation, based on data from customs seizures in OECD countries, did not include fake and pirated goods which were made and sold in the same country.
Digital products, distributed via the internet, were also not factored into the total.
"If these items were added, the total magnitude of counterfeiting and piracy worldwide could well be several hundred billion dollars more," the OECD said.
'Substandard and dangerous'
The OECD studied the problem for 18 months.
In addition to items such as computer software and DVDs, car parts, medicines and electrical components were among the types of goods identified by the report.
China was recognised as the largest source of pirated goods - accounting for about 86% of goods confiscated.
In other findings, the Middle East was identified as the biggest market for fake car parts, while the consumption of counterfeit cigarettes was highest in Latin America, Africa and Asia.
"Counterfeiting and piracy are illicit businesses in which criminal networks thrive," the report said.
"The report shows that the items that they and other counterfeiters and pirates produce and distribute are often substandard and can even be dangerous."
The International Chamber of Trade (ICC) welcomed the "comprehensive and thorough investigation of the problem" and also called on governments to act swiftly to crush these crimes.
The world business body estimated the total value of counterfeit and pirated goods worldwide is more than $600bn, but even this was the "tip of the iceberg".
It said the OECD failed to factor in the broader impacts - including those on employment, consumer health and safety and tax revenues.
"The costs to society and economies around the world are enormous," said ICC secretary general Guy Sebban.
A European Union study, published last month, found that the number of counterfeited items seized by customs officials had trebled in 2006 against the previous year.