Hyperbranched polyamidoamines (h-PAMAM) were prepared using a one-pot reaction to have similar molecular weight to third generation PAMAM (G3-PAMAM) dendrimers, and then functionalized with N-diazeniumdiolate nitric oxide (NO) donors. A wide range of NO storage capacities (∼1-2.50 μmol mg-1) and NO-release kinetics (t1/2 ∼30-80 min) were achieved by changing the extent of propylene oxide (PO) modification. The therapeutic potential of these materials was evaluated by studying their antibacterial activities and toxicity against common dental pathogens and human gingival fibroblast cells, respectively. Our results indicate that the combination of NO release and PO modification is necessary to yield h-PAMAM materials with efficient bactericidal action without eliciting unwarranted cytotoxicity. Of importance, NO-releasing PO-modified h-PAMAM polymers exhibited comparable biological properties (i.e., antibacterial action and cytotoxicity) to defect-free G3-PAMAM dendrimers, but at a substantially lower synthetic burden.