Historically, reference intervals (RI) have come from many sources and been generated by several methods and sample sizes. As RI generation has matured in human laboratory medicine, important guidelines have been adopted in veterinary medicine. Although meeting the goals of these guidelines may be difficult, especially with avian and exotic species, sets of 20 to 40 samples can be used with proper statistical calculations, and other viable alternatives have been examined. The adoption and knowledge of these different methods are important to make a positive move forward in RI generation for special species.