Immature malignant sacrococcygeal teratoma (SCT) is a rare tumor, deriving from the three germinal layers and is found in the sacrococcygeal region. It is the most frequent site of teratomas in the fetus. A nut-brown, solid tumor with cystic areas with a ten-cm diameter is reported in the sacrococcygeal region of a female fetus of 23 weeks and with a weight of 308 g. The ultrasound and pathology evaluations revealed characteristics of an immature malignant SCT. The incidence of this tumor type is one in 35,000 to 40,000 live births and females are four times more likely to be affected than males. Sacrococcygeal and cervical teratomas can be diagnosed by prenatal ultrasound and magnetic resonance imaging (MRI). Teratomas are considered an interesting field for research.