The increased exchange of agricultural goods and people has unleashed the spread of alien species in the Caribbean. The Dominican Republic, as well, has been burdened with the introduction of dozens of alien species, including a substantial number with high invasive potential. Some of these have caused significant economic losses to affected crops within intensive agro-ecosystems, and others have displaced native species, and/or interfered with the functioning of susceptible ecosystems. Herein we list about 50 cases of introduced agricultural pests including arthropods, molluscs, and plant pathogens causing fungal, bacterial, viral or other diseases. We briefly review selected examples with respect to their detection, impact and countermeasures taken. In most cases involving introduced alien arthropods, the lack of specialized antagonists, and/or the ineffectiveness of native antagonists have permitted rapid dispersal of the introduced pests. This has occurred in the cases of vectors of plant pathogens (aphids, and whiteflies), mealybugs, thrips, fruit flies, the coffee-berry borer, and recently the pigeon pea pod fly. Thus far, no introduced pests have been eradicated from the Dominican Republic. On the other hand, intentional or accidental introductions of antagonists of some introduced insect pests have resulted in dramatic population decreases of these alien species, often to levels well below economic-damage levels. This decrease has been achieved in the cases of the citrus blackfly, the citrus leafminer, the brown rice bug, and the papaya mealybug. Regarding the pink hibiscus mealybug, the combination of parasitoid species, probably introduced together with the pest, and the predacious mealybug destroyer already present since the 1930s, and the implementation of classical biocontrol have not permitted damage at levels comparable to those caused by this pest in the Lesser Antilles during the last decade.