This study distributed a questionnaire to cat or dog caregivers (owners) throughout Auckland, New Zealand, to investigate the attitudes of human companions toward the sterilization of their cats and dogs and the degree to which this occurs relative to demographic information gathered. A total of 276 recipients returned questionnaires with data pertinent to 477 cats and dogs. Female owners were more likely than were males to sterilize cats or dogs: 90.2% sterilization rate compared with 80%. Statistical trends also suggested that owners with a postschool education had a higher percentage of sterilized nonhuman animals than owners with no postschool or only school-age education. Cats were more likely than dogs to be neutered: 91.7% versus 78.5%. Companion animals not annually vaccinated were more likely to be sterilized than animals who were vaccinated annually: 93.6% and 85.4%. The study also showed gender bias and age differences in owner attitudes toward a number of the statements regarding sterilization, with male owners more likely to be concerned about the effect of neutering or spaying on the sexuality or masculinity of the animal.