OBJECTIVES: To establish the mode of inheritance and describe the clinical features of epilepsy in the Belgian shepherd, taking the outset in an extended Danish dog family (199 individuals) of Groenendael and Tervueren with accumulated epilepsy. METHODS: Epilepsy positive individuals (living and deceased) were ascertained through a telephone interview using a standardised questionnaire regarding seizure history and phenomenology. Living dogs were invited to a detailed clinical evaluation. Litters more than five years of age, or where epilepsy was present in all offspring before the age of five, were included in the calculations of inheritance. results: Out of 199 family members, 66 dogs suffered from epilepsy. The prevalence of epilepsy in the family was 33%. Fifty-five dogs experienced focal seizures with or without secondary generalisation, while four dogs experienced primary generalised seizures. In seven dogs, seizures could not be classified. The mode of inheritance of epilepsy was simple Mendelian. CLINICAL SIGNIFICANCE: This study identified that the Belgian shepherd suffers from genetically transmitted focal epilepsy. The seizure phenomenology expressed by family members have a strong resemblance to what has been reported for familial partial (focal) epilepsy in humans with variable foci with suggestion of linkage to chromosome 2 and chromosome 22q12.