Fetal tumors represent a rare and heterogeneous group of abnormalities. A significant proportion of them can now be diagnosed by using modern high resolution ultrasonic equipment. During 15 years there were 57 fetal tumours detected prenatally. Hygroma colli is the most frequent fetal tumor. It should be emphasized that cystic hygroma generally carries poor prognosis, and after an early diagnosis, termination of pregnancy is most logical approach. Contrary to the general opinion our own experience showed that there are cases in which prognosis could be much better as illustrated with our 4 cases. All of the treated fetuses, after surgical resection, had normal development and are now on the age of 5, 4, 3 and 2 years of life. An ovarian cyst can be suspected if a fluid-filled structure is visualized next to a fetal kidney and female external genitalia are recognizable. The ultrasound finding suggestive of an ovarian cyst is that of a pelvic cystic or complex mass in a female fetus with normal kidneys and urinary bladder and a normal gastrointestinal tract. In most cases, the normal course of fetal ovarian cyst is a spontaneous intrauterine or postnatal involution. Prenatal diagnosis improves neonatal outcome by allowing an appropriate choice of the optimal time, mode and place of delivery in order to avoid accidental and unexpected intrapartum and postnatal complications. The management of a fetus affected by an ovarian cyst depends on the size and on the echo-pattern of the cyst. It remains unclear whether in utero puncture of the cyst and evacuation of its content should be justified in cases of particularly large ovarian cyst. In our opinion intrauterine procedure can be attempted in the presence of large cyst fulfilling the fetal abdomen. We have treated actively two cases of large ovarian cysts by ultrasonically guided puncture before delivery and both fetuses underwent surgery later without complications. If properly performed puncture of the cyst seems to be a low risk procedure in comparison to potential problems that cyst may cause to the fetus or by causing dystocia. Sacrococcygeal teratoma represents the most frequent tumor in the fetuses and newborns. Prenatal diagnosis is usually simple and based on the visualization of tumor of variable size and internal structure. Tumors may appear as completely cystic, mixed or predominantly solid with obvious calcifications. Cystic and calcified tumors are most likely to be benign. Obstetrical management of sacrococcygeal teratoma depends on numerous parameters which include size and texture of the tumor, and gestational age.(ABSTRACT TRUNCATED AT 400 WORDS)