Claims for healthcare services are produced for virtually all aspects of medical care. Legal nurse consultants (LNCs) may be asked by insurers (government, commercial healthcare, liability), attorneys (both plaintiff and defense), practice groups, and facilities to analyze billing charges and procedure codes in the context of the related medical documentation. The LNC’s clinical knowledge and experience is critical to conducting bill reviews. This, coupled with knowledge of procedure and diagnosis codes and the ability to identify patterns and trends, prepares the LNC to recognize billing errors, such as billing for services which were not reasonable or medically necessary when compared with documentation in the medical record. This chapter discusses the process of analyzing claims for healthcare services and introduces methodology and practical considerations.