Psychiatric disorders of parents are associated with an increased risk of psychological and developmental difficulties in their children. Most research has focused on mothers, neglecting psychiatric disorders affecting fathers. We review findings on paternal psychiatric disorders and their effect on children's psychosocial development. Most psychiatric disorders that affect fathers are associated with an increased risk of behavioural and emotional difficulties in their children, similar in magnitude to that due to maternal psychiatric disorders. Some findings indicate that boys are at greater risk than girls, and that paternal disorders, compared with maternal disorders, might be associated with an increased risk of behavioural rather than emotional problems. Improved paternal mental health is likely to improve children's wellbeing and life course.