Leukoreduced blood components are commonly manufactured via filtration. There are specifications for the residual leukocyte content of any final cellular blood component but not for residual clotting factors. Leukoreduced and nonleukoreduced platelet-poor plasma products were manufactured from filtered vs unfiltered platelet-rich plasma, respectively, using platelet leukoreduction filters. The leukoreduced plasma showed lower levels of factor VIII (75% ± 16% vs 88% ± 18%, P ≤ .05), factor XI (86% ± 9% vs 96% ± 10%, P ≤ .01) and factor VII (87% ± 14% vs 98% ± 11%, P ≤ .01). No difference was seen with factor X, factor V, or fibrinogen. Plasma filtered through a whole blood filter showed a reduction in factor V (105% ± 12% vs 124% ± 10%, P ≤ .01) but a minimal reduction in factor VIII (80% ± 5% vs 82% ± 6%, P = .04). Filtration can alter the residual levels of clotting factors to a variable extent in manufactured plasma, most noticeably factors V, VII, VIII, and XI.