| Named By: | George Gaylord Simpson in 1933 |
| Time Period: | Coniacian-Late Eocene (Casamayoran)~89.3-37.2 Ma |
| Location: | Worldwide paticularly across southern continents with locations including Argentina, Brazil, Spain, India, Niger and Madagascar |
| Size: | Uncertain due to incomplete remains, but width of vertebra indicates a large size |
| Diet: | Carnivore |
| Fossil(s): | Scattered vertebra |
| Classification: | | Chordata | Reptilia | Squamata | Scleroglossa | Serpentes | Madtsoiidae | |
Madtsoia is an extinct genus of madtsoiid snakes. It is known from the Eocene (Casamayoran and Itaboraian) of Argentina (M. bai), the Paleocene of Brazil (M. camposi), the Late Cretaceous (Campanian) of Spain (M. laurasiae), the Late Cretaceous of India (M. pisdurensis), and the Late Cretaceous (Maastrichtian) of Madagascar and the Coniacian of Niger (M. madagascariensis). Recovered vertebrae of M. pisdurensis are 1.83 centimetres (0.72 in) long and 4.35 centimetres (1.71 in) tall) and pertain to a snake that was approximately 5 metres (16 ft) long.