Background: Good sibling relationships in adulthood are known to be a protective factor for mental health.Two axes make up this thesis. The first examined and compared the sibling relationships of people with and without schizophrenia. The second axis highlighted the intrafamilial relational experience of these non-sick brothers and sisters. Method: In the first axis, we carried out a statistical comparison between two groups of brothers and sisters on the quality of their fraternal relationships, emotional distress and self-esteem. We also looked for the determinants of these fraternal relationships. In the second axis, we questioned brothers and sisters about their intra-family relationships. Results: The results of the first axis reveal that the fraternal relationships of people suffering from schizophrenia are of lower quality than those of the general population and fuel the level of emotional distress. The results of the second axis highlight the impact of the diagnosis of schizophrenia on the past and present history of the family. The brothers and sisters look in the past for events that may have precipitated the illness. As they consider the present, they make every effort to restore family homeostasis. Conclusion: The results of our research highlight the emotional difficulties experienced by adult siblings of people with schizophrenia. The very effect of acknowledging their existence and their issues could help brothers and sisters to feel legitimate in the face of their difficulties.