Congenital factor XIII (FXIII) deficiency is a rare condition with substantial risk for life-threatening bleeding. Replacement of deficient FXIII with plasma-derived FXIII concentrate is a treatment option. The current 12-week study evaluated the steady-state pharmacokinetic (PK) and safety profile of prophylactic infusions of FXIII concentrate (human) in patients with congenital FXIII deficiency. Patients received FXIII concentrate (human) 40 IU kg−1 on Days 0, 28, and 56. FXIII levels were assessed before and after each infusion; steady-state PK parameters were assessed up to 28 days after the infusion on Day 56. Treatment effectiveness in maintaining trough FXIII activity levels ≥5% over 28 days and safety parameters were also assessed. Fourteen patients received FXIII concentrate (human) and 13 completed the study. Post-infusion, FXIII activity levels increased to within the range found in patients without congenital FXIII deficiency without reaching supra-therapeutic levels. Non-baseline-adjusted trough FXIII activity levels were maintained at or above 10% at all post-baseline visits in all patients. Steady-state PK parameters were baseline-adjusted; maximum FXIII activity was 87.7% at 1.72 h post-infusion, subsequently declining to a minimum of 5.0%. The half-life was 6.6 days. FXIII concentrate (human) was generally well tolerated. Two patients had possibly treatment-related adverse events. There were no reports of thromboembolism, viral transmission, bleeding events or treatment-related hypersensitivity. These findings support use of FXIII concentrate (human) 40 IU kg−1 every 28 days as an appropriate regimen for routine, long-term prophylaxis in children and adults with congenital FXIII deficiency. Clinical trial registration: www.clinicaltrials.gov/ct2/show/NCT00883090.