The prenatal developmental toxicity potential of alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC) was evaluated in regulatory-compliant studies. Pregnant female CD rats (25/group) and New Zealand White rabbits (16/group) were administered ADBAC (0, 10, 30, or 100 mg/kg/day and 0, 1, 3, or 9 mg/kg/day, respectively), or DDAC (0, 1, 10, or 20 mg/kg/day and 0, 1, 3, or 10 mg/kg/day, respectively), by oral gavage on gestation days (GD) 6-15 for rats and GD 6-18 for rabbits. At scheduled termination (GD 21 for rats; GD 29 for rabbits), maternal necropsies were conducted and live fetuses were weighed and examined for external, visceral, and skeletal malformations and variations. Clinical signs of maternal toxicity were observed in rats and rabbits dosed with ADBAC, resulting in no-observed-adverse-effect levels (NOAELs) of 10 and 3 mg/kg/day, respectively. Despite the treatment-related maternal toxicity of ADBAC, the NOAEL for prenatal developmental toxicity was 100 and 9 mg/kg/day for rats and rabbits, respectively, the highest doses evaluated. Repeated oral doses of DDAC resulted in maternal toxicity in both species at the top two doses, with 25% mortality noted in rabbits at 10 mg/kg/day. No teratogenic effects were observed at any dose for either species. However, increased incidence of dead fetuses per litter and decreased fetal body weights were observed in rabbits at the maternally lethal dose of 10 mg/kg/day. The NOAEL for maternal toxicity of DDAC was 1 mg/kg/day for both species and the NOAEL for prenatal developmental toxicity was 20 and 3 mg/kg/day, for rats and rabbits, respectively.