Spinal nerve root compression (SNRC) lesions resulting from various etiological conditions are a problem affecting many patients seen by physical therapists. The purposes of this article are to describe the factors that determine the strength deficits (SDs) accompanying these lesions and to discuss evaluation procedures and therapeutic considerations for patients with these SDs. Because of biological compensatory mechanisms and the shortcomings of techniques for measuring SDs, physical therapists may be unaware of the motor involvement of patients with SNRC lesions. The application of appropriate evaluation procedures should enable physical therapists to identify the SDs and monitor their response to therapeutic interventions. These interventions should be applied with appreciation of the potential for causing further damage from overworking the weakened muscles.