Pathogen inactivation (PI), or pathogen reduction technology, reduces the infectious risk of plasma and platelet transfusions, and also affects clotting factor activities and platelet viabilities. Plasma is treated with solvent-detergent to disrupt enveloped viruses, or with photoactive agents methylene blue plus light, or amotosalen (AM) or riboflavin (RF) plus ultraviolet (UV) light, to disrupt pathogen nucleic acids. PI plasmas have average clotting factor activities of 75 to 85% of untreated plasma. PI plasmas are generally equivalent to regular plasma in randomized clinical trials (RCTs) in regard to coagulation test corrections and bleeding outcomes, except for one trial in which RF plasma was inferior for prothrombin time correction. Platelets are treated with UV plus RF or AM. In RCTs, the mean 1-hour corrected count increments from PI platelets are 66 to 94% (trials median, 75%) of those from untreated platelets. PI platelets also have lifespans of 4 to 5 days after 5 days of storage, compared with 6 to 7 days for untreated platelets. Bleeding outcomes comparing PI versus non-PI platelets in RCTs have been equivalent, except one study with more bleeding on AM platelets. Platelet treatment with UVC light alone for PI has entered clinical trials.