Similarity of pathology and disease progression make the non-human primate (NHP) model of Lyme neuroborreliosis appropriate and valuable. In the NHP model of Lyme neuroborreliosis, spirochetal density in the nervous system and other tissues has been measured by polymerase chain reaction and correlated to anti-Borrelia burgdorferi antibody in the serum and cerebrospinal fluid and to inflammation in tissues. Despite the demonstrable presence of Borrelia burgdorferi, the causative agent of Lyme borreliosis, only minor inflammation of the central nervous system occurs, though inflammation can be demonstrated in other tissues. Infected animals also develop anti-Borrelia burgdorferi antibody in the serum, although increased amplitude of antibody is not predictive of higher levels of infection. The NHP model continues to provide important insight into the disease process in humans.