Using national register data between 2006-2014, we investigated the relationship between outpatient mental health service use (a proxy for mental disorder) and subsequent marital separation among women in Norway and whether the strength of the association differed for migrant and non-migrant women. Our sample population included 679,928 married women aged 18-60 years. Service use was strongly associated with marital separation among all women. The relationship was stronger for Filipinas but weaker for Somalis and Russians, compared with non-migrant women. Migration-related factors may influence marital separation among migrant women and barriers to care are likely to exist.