Quasipalindromes, or imperfect inverted repeats, undergo spontaneous mutation to more-perfect inverted repeats. These mutations have been observed in many organisms, ranging from bacteria to humans, where they are associated with mutations leading to disease. We determined the relative frequency of quasipalindromes and perfect palindromes in more than 100 sequenced prokaryotic genomes. In nearly all cases, perfect palindromes were relatively more frequent than quasipalindromes, suggesting that quasipalindrome correction is a general mechanism for mutation in prokaryotes.