The study area pertains to the Chocó Biogeography, one of the most biodiverse areas in the world, where around 40,000 ha of rainforest has been cleared for oil palm plantations. We surveyed the ant species' richness and diversity in four differently disturbed areas in Tumaco, Colombia, using pitfall traps and Winkler sacks. Study sites were two oil palm plantations of three- and seven- years' existence, a peach palm plantation Bactris gasipaes of 20 years, and an area of secondary forest of 10 years. A total of 93 ant species or morphospecies, comprising 31 genera in 8 subfamilies were identified. The subfamily Myrmicinae had the highest number of species (57), followed by Ponerinae (10) and Formicinae (9). The hybrid palm oil plantations harbored 46 species (7 years) and 50 species (3 years), respectively, while the peach palm plantation was composed of 53 species, and the secondary forest had 62 species. Ectatomma ruidum was the most dominant species in the oil palm plots (> 80% of specimen), but significantly less in the peach palm and secondary forest. The most species rich genera were Pheidole spp. (23) and Solenopsis spp. (13). No differences were observed in the ant species' diversity between the secondary forest and peach palm, contrasting with the significant differences between the secondary forest and the two oil palm areas. A comparison with studies in natural areas suggests that the oil palm monocultures have dramatically reduced the species' richness and that ten years of recovery does not bring back anything close to the original diversity.