Many researchers have studied somatic symptoms in children. However, its association with severe mood dysregulation (SMD) is poorly known. The aim of this study is to detect the presence of SMD in preschool children and to know the prevalence of somatic symptoms and associations with psychopathology, SMD, and aggressiveness. The study population consists of children between 3 to 6 years of age enrolled in Barcelona's kindergarten schools (n = 319). Their parents completed questionnaires about the presence of somatic symptoms in children, absences from school and pediatric visits, child psychiatric symptoms, presence of symptoms of SMD, and aggressiveness. Teachers were also informed about SMD and aggressiveness. Children who complained frequent somatic symptoms (three or more in the last 2 weeks) were compared with those who did not. Two hundred five children (64.3%) reported at least one physical complaint in the 2 weeks preceding the study. One hundred participants (31.3%) reported frequent somatic complaints. Positive associations were found with anxiety symptomatology, separation anxiety, social phobia, pediatric visits, and school absences, but not with aggressiveness or SMD symptoms. Somatic symptoms are common in a sample of preschool children but do not show a positive association with the symptoms of SMD.