Treating patients in rehabilitation settings is becoming increasingly complex for a variety of reasons, such as the presence of several comorbid conditions, increased age, and earlier discharge from acute care facilities. As a result, careful monitoring and assessment by nurses is essential. Laboratory testing can improve the assessment when nurses are able to recognize when and what should be reported and what types of treatments may be needed. Understanding what laboratory findings should be monitored and what added assessment criteria are necessary can be daunting. Therefore, this article reviews critical laboratory and other assessment findings in light of common health problems faced by patients in rehabilitation settings. A case study is used to highlight the importance of laboratory testing.