In 2003 the Texas Board of Health approved a modification to the Texas Administrative Code that permitted pet owners to have their dogs (Canis familiaris) and cats (Felis catus) vaccinated against rabies every 3 years, provided a triennial vaccine was used. The change had been opposed by hundreds in the veterinary community, some concerned that its implementation would be followed by a decrease in rabies vaccination rates. To determine if this decrease had occurred, rabies vaccination rates for 4 years before and after migration to the 3-year vaccination interval were examined. Data for dogs and cats, ≥4 months of age, were collected from the Texas Department of Health Rabies Incident Report database. Each animal’s record included its current rabies vaccination status. The number of animals that were currently vaccinated against rabies was tallied and the percent vaccinated was calculated. From 1999 through 2002, 46% of dogs were vaccinated against rabies. From 2004 through 2007, 56% of dogs were vaccinated against rabies. From 1999 to 2002, 18% of cats were vaccinated against rabies. From 2004 to 2007, 30% of cats were vaccinated against rabies. There has been a significant increase in the numbers of dogs (P < 0.001), and cats (P < 0.001), vaccinated against rabies since the introduction of the triennial vaccination interval. This observational study documents the positive changes in rabies vaccination rates following migration from a 1-year to 3-year vaccination interval.