This invention is directed to N-acylpyrrolidin-2-ylalkylbenzamidine derivatives which useful for inhibiting the activity of Factor Xa, by contacting said derivatives with a composition containing Factor Xa. The present invention is also directed to compositions containing said derivatives, methods for their preparation, their use, such as in inhibiting the formation of thrombin or for treating a patient suffering from, or subject to, a disease state associated with a physiologically detrimental excess amount of thrombin.