Akabane virus, a member of the Orthobunyavirus genus in the family Bunyaviridae, causes congenital abnormalities and arthrogryposis with hydrocephalus or hydroencephaly in ruminants. Tis study intends to describe the clinical signs, gross and histopathological features seen in 25 afected lambs in an outbreak of congenital arthrogryposis with hydrocephalus or hydranencephaly in Al-Muthanna governorate, Iraq afer a large number of stillbirths and musculoskeletal deformities from October 2017 to May 2018. Skeletal muscle hypoplasia was seen in the limbs of the afected lambs accompanied with severe arthrogryposis and gross visible brain malformations. In addition, fetal mummifcations, stillbirths, and dead lambs were also seen. Te most histopathological features in muscle fbers were degenerative lesions and absences of cross-striation accompanied with mild infltration of neutrophils and mononuclear cells in severely afected lambs. Te meninges of afected lambs revealed fused membranes with focal areas of fbrous thickenings and necrotic debris. In conclusion, according to clinical signs, gross and histopathological investigations, Akabane virus, a member of the Orthobunyavirus genus in the family Bunyaviridae, causes congenital abnormalities and arthrogryposis with hydrocephalus or hydroencephaly in ruminants and could be the cause of this outbreak, although future studies must be performed to confrm the etiology of this outbreak. Moreover, other causes of hydrocephalus or cerebellar malformation, such as Schmallenberg virus, bluetongue virus and border disease virus and teratogenic plants that lead to arthrogryposis, have to be investigated. Also, the authorities should take prevention and control measurements to stop the replication of arthropod vectors.