Hi,
Wireless Mobile Mouse 3500 - has a 3 year warranty.
Microsoft Hardware Warranties
http://www.microsoft.com/hardware/Warranties.mspx
These mice come with 90 tech support from day of 1st incident which would
start when you contact Microsoft at the below number.
MS Hardware Support and Warranty Claims
Tech Support 1-800-936-5700 for MS Hardware.
Hope this helps.
Rob Brown - Microsoft MVP <- profile - Windows Expert - Consumer : Bicycle <- Mark Twain said it right!