A member of the genus Oryzomys within the family Cricetidae, it is similar to O. couesi of mainland Central America, from where it may have dispersed to its island during the last glacial period.

The species probably became extinct late in the 19th century, perhaps due to the introduction of the small Indian mongoose, competition with introduced rodents such as the brown rat, and habitat destruction.

The species differed from O. couesi in having longer nasal bones, shorter incisive foramina (perforations of the front part of the palate), and more robust zygomatic arches (cheekbones).

In his 1877 monograph on North American rodents, Elliott Coues mentioned two specimens of Oryzomys from Jamaica in the collections of the United States National Museum (USNM).

According to Coues, the specimens were similar to the marsh rice rat (Oryzomys palustris) of the United States, but different in color.

Thomas suspected that the species was already extinct on Jamaica, but that it or a similar rice rat could still be found in the unexplored interior of Cuba or Hispaniola.

[3] Revising North American Oryzomys in 1918, Edward Alphonso Goldman retained O. antillarum as a separate species, but conceded that it was so similar to mainland O. couesi that it may have been introduced on Jamaica.

[9] In 1920, Harold Anthony reported that remains of O. antillarum were common in coastal caves, suggesting that the species had previously been an important part of the diet of the barn owl (Tyto alba).

[5] In a 1993 review, Gary Morgan reinstated the animal as a distinct species closely related to O. couesi, citing an unpublished paper by Humphrey, Setzer, and himself.

[6] Guy Musser and Michael Carleton, writing for the 2005 third edition of Mammal Species of the World, continued to classify the Jamaican form as part of O. couesi, but did not reference Morgan.

[6] However, a site (Wallingford Roadside Cave) from the last interglacial, the Eemian, contains only the hystricognath rodents Clidomys and Geocapromys browni and lacks Oryzomys.

[32] The presence of the rice rat on Jamaica before the arrival of humans disproves the hypothesis that it was introduced; instead, it must have reached the island by overwater dispersal through a rafting event, probably less than 125,000 years ago.

[6] From its common and widespread occurrence in caves, Ray suggested that the rice rat occurred in many different habitats before European contact.

[36] Patrick Browne, in the 1756 Civil and Natural History of Jamaica, described a "House and Cane-Rat", a "Mouse", and a large "Water-Rat", which he said had been introduced to the island and become very common there.

[46] Gosse wrote that an early explorer, Anthony Robinson, had described and pictured this species in an unpublished manuscript, on the basis of a specimen 20 inches (51 cm) long, half of which consisted of the tail.