We investigated the relationship between the risk of deep infection and intraoperative use of laminar airflow systems and body exhaust suits during 8,288 total knee replacements performed in 256 hospitals. The overall 90-day cumulative incidence of deep infection requiring subsequent operation was 0.34% (28 procedures). In all combinations of laminar airflow systems and body exhaust suits, the 90-day cumulative incidence of infection requiring subsequent operation was 0.27%-0.43%. The risk ratio was 1.57 (95% confidence interval, 0.75-3.31) for laminar airflow systems and 0.75 (95% confidence interval, 0.34-1.62) for body exhaust suits suits. The risk was not statistically associated with use of either method, but infections were rare.