Use of animals for therapeutic purposes, animal assisted therapy or AAT is a method for improving quality of life for long-term inpatients. The object of this paper was to evaluate dog companionship as a form of AAT and its effects on perception of loneliness in geriatric nursing home residents. The participants were involved in a six-month program of dog companionship three times weekly for 90 minutes. There were 21 residents included in the program, with a mean age of 80 years. Loneliness was measured by the short version of the UCLA Scale of loneliness. Comparison of test results before and after participation in the program showed that dog companionship reduces the perception of loneliness.