Platelet-rich plasma (PRP) as a clinical treatment for bone, muscle, tendon, and cartilage injury has gained popularity in the field of orthopedic sports medicine. The use of a patient's own blood is an appealing aspect of PRP treatment, as the resulting plasma preparation is considered relatively benign in comparison with more common, potentially caustic treatments such as corticosteroids and anesthetics. Although appealing, the autologous nature of PRP introduces variability to plasma preparations, creating challenges for both the researcher and the clinician. Differences in patients at the time of blood draw result in plasma preparations that vary within as well as between patients. This variability is compounded by the multitude of protocols and devices available for procuring PRP. The variability of components and its effects on dosage should be considered in single or consecutive treatments of PRP.