Aortic aneurysm (AA) and atherosclerosis (AS) of various vascular beds are asymptomatic for a long time and are relatively common pathological conditions that lead to life-threatening and disabling complications. In this review, we discuss the current understanding of the high variation in direct and inverse comorbidity of AA and AS as presented in scientific publications. Estimates of AA and AS comorbidity depend on several factors, such as the location of AA (ascending or descending thoracic aorta or abdominal aorta), familial or sporadic cases of AA, syndromic forms of AA, and/or aortic valve pathology (bicuspid aortic valve [BAV]). To identify the causes of the comorbidity of AA and AS, it is important to consider and characterise many factors in detail. These factors include clinical characteristics of the patients included in a study (age, sex) and risk factors (mainly the presence of monogenic forms and BAV, hypertension, hypercholesterolaemia, diabetes mellitus, and cigarette smoking). Additionally, it is essential to consider characteristics of the disease course and the nature of multimorbidity and to take into account pathologies not only of the cardiovascular system but also of other organ systems, with special attention to metabolic and endocrine disorders.