Ultrasound examination of the ovaries was performed monthly in the fol
licular phase of 139 healthy adolescents for one years. In 17 girls (1
2,2%) ovarian cysts spontaneously disappeared within 3 months of first
observation. In 6 subjects, treatment with the combined estrogen/prog
estogen pill was given. The treatment was effective in 4 girls after 2
-6 months while 2 subjects required surgical intervention for a cystic
teratoma and a simple follicular cyst respectively. A spell of serial
sonographic observation of ovarian cysts would seem appropriate in ad
olescents.