The Tsagaantsav Formation, Tsagantsab Formation or Tsagan-Tsab Formation (Russian: Tsagaantsav Svita) is an Early Cretaceous (Hauterivian to Barremian) geologic formation in Mongolia. Indeterminate sauropod and psittacosaurid remains have been recovered from the formation. Remains of the pterosaur Noripterus, which were originally given their own genus, "Phobetor" have also been recovered from the formation.
Graham et al. 2001 reported radiometric dates of 131 and 126 Ma from the formation.
The following fossils were reported from the fluvial to lacustrine sandstones and siltstones of the formation: