Administration of 167 mg/kg Tetrahydrouridine (THU) followed by 1.0 mg/kg DAC results in death in one male and eight females. Animals surviving to scheduled termination are generally asymptomatic with no treatment related effects observed in body weights, food consumption, clinical chemistry and urinalysis for a treatment up to 1.0 mg/kg DAC in combination with 167 mg/kg Tetrahydrouridine in animals.