The Old English fricative voicing rule (FVR) has been variously formulated in both linear and nonlinear frameworks, yet to no complete satisfaction. Moreover, no attempt has yet been made to define the nature of the FVR and its status in lexical phonology. The peculiarity of the rule is that it has both lexical and postlexical properties. In general, a lexical rule is structure preserving and a postlexical rule nonstructure preserving; hence, a lexical rule should not create novel allophonic, nonneutralizing segments absent from the underlying inventory. However, unlike other non-structure-preserving rules, the FVR does not apply across the board-it applies only lexically, inside morphemes in nonderived words or stems and in derived words only across inflectional suffix boundaries.In the following discussion, linear and nonlinear versions of the FVR are first reviewed, followed by the restatement of the FVR as lexical but noncyclic and nonstructure preserving-that is, as a word-level rule that applies at level 3 to nonderived and derived forms. It is argued that since the rule introduces nondistinctive segments, it is therefore problematic for both the strict cycle condition and structure preservation, but if the rule operates on underspecified segments, all these problems can be avoided.