A European Union court has upheld most of a $A1 billion competition fine against Microsoft.
In a ruling on Wednesday, it rejected Microsoft's appeal against the 2008 ruling.
It, however, cut the fine by 39 million euros ($A48.74 million) to 860 million euros ($A1.07 billion).
The fine is technically a "penalty for noncompliance" with a 2004 order by the EU competition watchdog for Microsoft to make code available for its server software that would allow competitors' products to interface properly.
Wednesday's decision "essentially upholds the commission's decision and rejects all the arguments put forward by Microsoft in support of annulment", the court in Luxembourg said.