This study investigated the effects of adding waste plastic bottles to asphalt mixtures. Various percentages of crushed plastic bottles (0-1%) were added to asphalt mixtures. Test results showed that adding lower amounts (0.2-0.6%) of plastic bottles increased mixture stability and bulk specific gravity. However, higher plastic amounts (>0.6%) decreased stability and specific gravity. Mixtures with plastic also had lower optimum asphalt contents. Stiffness initially increased with lower plastic but decreased at higher amounts. Fatigue life significantly increased for mixtures with plastic bottles, more than doubling at some stress levels. In conclusion, adding appropriate amounts of waste plastic bottles provided benefits to asphalt mixture properties including increased stability,