The rarity of infantile ovarian cystadenoma (CA) accounts for the very little knowledge about their behaviour. The aim of this retrospective study is to highlight the modes of presentation and to evaluate the treatments and the recurrence risks of these benign tumours. Relation to adult epithelial ovarian tumours is discussed. The medical records and imaging studies of 42 CA in 31 children less than 16 years of age operated at our institution between 1985 and 2003 were retrospectively evaluated. Mean age of first surgery was 11.5 years. 7/31 girls (22.6%) presented with a bilateral CA, four of them were synchronous. 8/42 (19%) CA were in torsion at surgery, conservative management was possible in four cases. 31/42 (74%) CA were treated conservatively. 4/42 CA recurred 1-3.5 years after complete cyst removal. All were endocervical type CA, there was no intestinal type. The 42 CA were serous in 18/42, mucinous in 23/42 and unqualified in one. Mucinous epithelial cells were often sparse and focal along the cyst wall. Four CA presented with micropapillae in post-pubertal girls. No borderline tumours were observed. Mucinous cystadenomas (MCA) are better described as seromucinous cystadenoma (SMCA) because of the mucinous cells localisation. CA occurs early in life, we surmise that they may need hormonal stimulation to develop micropapillae. Complete removal of these potentially low-grade malignant ovarian tumours precursors is advocated. Conservative surgery is recommended to preserve ovarian function.