Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela.
Northern and eastern Colombia and northern and central Venezuela east to Trinidad and the Guianas, southern irregularly to eastern Ecuador, north-eastern Peru, northern and eastern Bolivia, northern Argentina, Paraguay and south-eastern Brazil.
 
Population
Estimated population is unknown (2010).
White-headed Marsh Tyrant (Arundinicola leucocephala) [XC761493]
by Fernando Igor de Godoy from Taquaral de Goi\u00e1s, Taquaral de Goi\u00e1s, Goi\u00e1s, Brazil (call, song)
White-headed Marsh Tyrant (Arundinicola leucocephala) [XC879286]
by Andrew Spencer from Fazenda Rio Negro, Rio Negro, Aquidauana, Mato Grosso do Sul, Brazil (chasing call)
Subspecies
No subspecies.
Genus related to Fluvicola and sometimes merged with it. However, anatomical evidence and behaviour suggest that separate generic treatment is more appropriate.