The sooty-fronted spinetail (Synallaxis frontalis) is a species of bird in the Furnariinae subfamily of the ovenbird family Furnariidae.

[2][3] The Clements taxonomy recognizes two subspecies, the nominate S. f. frontalis (Pelzeln, 1859) and S. f. fuscipennis" (Berlepsch, 1907).

Their wing coverts are dark rufous and their flight feathers tawny-rufous with dusky tips.

[5][6][7] The sooty-fronted spinetail is found from northeastern Brazil (Maranhão to Rio Grande do Norte) southwest in a wide swath through Brazil, eastern Bolivia, most of Paraguay, essentially all of Uruguay, and into Argentina to northern Buenos Aires Province.

[5][6][7] The sooty-fronted spinetail is a year-round resident in most of its range, though the farthest southern sub-population might make some northern movement after the breeding season.

It usually forages in pairs, apparently gleaning prey from foliage and small branches and sometimes the ground.

Its nest is a globe of thorny twigs with an entrance tube at the side and an inner chamber lined with dead leaves, moss, feathers, and other soft materials.

What appears to be the sooty-fronted spinetail's song is variously described as " 'ka-kwee-éék', 'ka-kweek', 'pi-whéé', or 'ja-coo-éé' "[5], a "very high 2-noted 'du-Twee' "[6], and "a slow, deliberate teeoopooee"[7]>!-- -->.