Sodium bicarbonate and potassium bicarbonate are systemic anticoagulants that when administered internally inhibit blood coagulation in man and in warm-blooded animals. As such, they are useful and effective in the treatment and/or prevention of thromboembolic diseases, myocardial infarction or other conditions associated with high risk of thromboembolism. Sodium bicarbonate is especially useful for preventing clotting of ptient's blood during kidney dialysis and for preserving citrated human or animal whole blood and plasma indefinitely under proper storage conditions.