The present exploratory project represents a cross-sectional study designed to determine the percentage of people reporting significant symptoms of complicated grief (CG) and/or posttraumatic stress disorder (PTSD) in response to the death of companion pets/animals. Human participants (N = 106) were sampled from a veterinary clinic. Fifty-two percent of participants had lost one to three pets from natural causes, 60% had never lost a pet to euthanasia, and 37% had lost one to three pets to euthanasia. The study suggests that many people experience significant attachment to their pets/animals and experience significant features of grief reactions (about 20%) after the death of a pet/animal. However, the percentage of people experiencing major pathological disruption is relatively low (<5%-12%). Thus, subclinical levels of grief and sadness are relatively common human responses to the death of companion pets/animals and last 6 months or more for about 30% of those sampled. Severe pathological reactions do occur but are quite rare among human survivors. Implications for mental health clinicians working with affected populations are discussed.