Apple has said that "some batteries" in its range of MacBook and MacBook Pro laptops have "performance issues".
The company has issued a software update to fix the issue and has offered to replace defective batteries.
"The factors causing the performance issues do not present a safety risk. You may continue to use your current battery," the company said.
Reports of problems, including swollen batteries, have been circulating since the laptops were launched in 2006.
In its support notes to users, Apple says battery packs which are "visibly deformed" are among the symptoms of battery problems.
The company advises users to install the update on all "MacBook and MacBook Pro computers and extra batteries that were purchased between February 2006 and April 2007".