Lawyers participating in legal malpractice litigation sometimes encounter evidence of serious disciplinary rule violations. Whether, and how soon, those lawyers are required to report this information to grievance authorities is a question that has received little attention from courts and scholars, despite the fact that most states have mandatory reporting rules. The dilemma for lawyers serving as testifying experts is particularly troublesome because nonreporting may result not only in discipline, but testimonial impeachment. The better view is that an expert in a pending case ordinarily has no mandatory obligation to report misconduct. This conclusion is supported by an analysis of the narrowness of the reporting obligation, the exceptions to the rule, public policy considerations related to malpractice litigation and grievance procedures, and customary professional practices. However, after litigation ends, an expert (and other lawyers) may have a duty to call evidence of serious misconduct to the attention of disciplinary authorities.