Starting from known piperidine renininhibitors, a new series of 3,9-diazabicyclo[3.3.1]nonene derivatives was rationally designed and prepared. Optimization of the positions 3, 6, and 7 of the diazabicyclonene template led to potentrenininhibitors. The substituents attached at the positions 6 and 7 were essential for the binding affinity of these compounds for renin. The introduction of a substituent