Gambling disorder is characterized by a behavioural pattern of dysfunctional gambling that persists despite its negative implications in different areas of people’s daily life. One of the most negatively affected areas is the one related to family members. This study aimed, firstly, to study the differences between family members of people with gambling disorder and a general population sample in anger (state, trait, expression-out, expression-in. control-out and control-in), rumination (brooding, reflection and total), and anxiety and depression. The second aim was to analyse the correlation between these variables in the family members of people with gambling disorder, and thirdly, to analyse the mediating role of rumination between anger, anxiety and depression. This study consisted of 170 people, of whom 87 were family members of people with a gambling disorder, and 83 were from the general population. Instruments measuring anger, anxiety, depression, and ruminative responses were administered. Results showed that family members had significantly higher scores in anger (state), depression, anxiety, rumination (total and brooding). Also, results showed that anger correlated positively and significantly with rumination, depression and anxiety, which also correlated positively and significantly with each other. Third, rumination mediated the relationship between the following variables: anger (state) and depression; anger (trait) and anxiety and depression; anger (external expression) and anxiety and depression. A complete mediating effect was found in the latter case and a partial mediating effect in the first two cases. In conclusion, it is found that having a family member with a gambling disorder may increase levels of anger, anxiety, depression and rumination. Furthermore, it is shown that working on rumination may reduce depression and anxiety in family members of gamblers.