The Parsley massacre was a mass killing of Haitians living in the Dominican Republic's northwestern frontier and in certain parts of the contiguous Cibao region in October 1937. Dominican Army troops from different areas of the country carried out the massacre on the orders of Dominican dictator Rafael Trujillo. As a result of the massacre, virtually the entire Haitian population in the Dominican frontier was either killed or forced to flee across the border. Many died while trying to flee to Haiti across the Dajabón River that divides the two countries on the island; the troops followed them into the river to cut them down, causing the river to run with blood and corpses for several days. The massacre claimed the lives of an estimated 14,000 to 40,000 Haitian men, women, and children. Dominican troops interrogated thousands of civilians demanding that each victim say the word "parsley" (perejil). If the accused could not pronounce the word to the interrogators' satisfaction, they were deemed to be Haitians and killed.

The Haitian minority of the Dominican Republic is the largest ethnic minority in the Dominican Republic since the early 20th century.