Cardiac pathologies are the major aspect in the treatment strategies for Marfan syndrome (MFS). In this progressive disease, less is known about manifestations and progression of cardiovascular symptoms in children. To define a certain decision regarding therapeutic options, knowledge concerning the onset of cardiovascular findings is essential. From 1998 to 2011, suspected pediatric Marfan patients were subjected to a standardized diagnostic program. Cardiovascular findings were analyzed in terms of age at first clinical manifestation, prevalence and gender differences, morbidity, mortality, and treatment. Marfan syndrome was diagnosed in 82 patients (46 boys; mean age at diagnosis, 9.0 ± 5.7 years). At first presentation, aortic root dilation was found in 56 % of patients, mitral valve prolapse in 31 %, whereas pulmonary artery dilation was detected in 22 % and tricuspid valve prolapse in only 17 % of patients. Aortic (2.5 %) and mitral valve regurgitations (22 %) are significantly correlated with aortic root dilation (p < 0.01) and mitral valve prolapse (p < 0.05) but without relevant progression during childhood. Prophylactic medication was initiated for 42 % of the patients (mean age, 8.0 ± 4.5 years) because of progressive aortic root dilation. Aortic dissection did not appear. Aortic root surgery was needed for 4 % of the patients. Gender-specific differences in cardiovascular findings, progression of disease, or treatment did not appear. Comparable with adults, aortic root dilation is the most frequent cardiovascular finding in children and associated with relevant morbidity, whereas aortic and mitral valve regurgitation are of minor clinical relevance. Manifestation at an early age and slow progression of cardiovascular findings underscore the necessity of repeated echocardiographic examinations for early diagnosis and start of prophylactic treatment.