Subtribe : ONCIDIINAE : Largest subtribe with nearly 1,000 species within about 56 to 78 genera, found in tropical America, the Caribbean and Florida. Most are epiphytes, but a few are terrestrials. They usually have short and stout pseudobulbs.

Alliance : ONCIDIUM : largest alliance; includes the majority of genera in cultivation.
Genera : Ada, Aspasia, Brassia, Cochlioda, Miltonia, Miltoniopsis, Odontoglossum, Oncidium (most)

Alliance : TRICHOCENTRUM
Genera : Trichocentrum

Alliance : COMPARETTIA
Genera : Oncidium, (equitants only), Comparettia, Ionopsis, Rodriguezia

Alliance : TRICHOPHILIA
Genera : Notylia, Psychopsis, Trichopilia Alliance : LOCKHARTIA Genera : Lockhartia

Alliance : HYBRIDS : over 107 hybrid genera.
Genera : Aliceara, Bakerara, Beallara, Brassidium, Burrageara, Colmanara, Degarmoara, Howeara, Maclellanara, Miltassia, Miltonidium, Odontioda, Odontobrassia, Odontocidium, Odontonia, Rodricidium, Rodrumnia, Trichocidium, Vuylstekeara, Wilsonara