Introduction: Perinatal period is the period that includes fetuses weighing > 500 grams (22^nd week of gestation) and newborns aged up to seven days. Perinatal mortality is one of the earliest quantitative measurements of quality in obstetric care and affects approximately 0.5% to 1% of all pregnancies. Aim: The purpose of this study was the identification, classification, and frequency of causes of perinatal mortality in premature infants during 20 years (1992-2012) in a tertiary Maternity Hospital in Athens. Materials and Methods: This was a retrospective study based on Pathology Department record and contains autopsy findings of fetuses, newborns, and membranes of the period 1992-2012 in conjunction with clinical information. The authors excluded pharmaceutical miscarriage and those containing vague variables. The total population birth to the mentioned years in this Hospital was 23,703 and there were 278 deaths. The authors used the classification system of ReCoDe (2005) which best suited the present data. Changes in perinatal death cause were estimated and compared every five years during this period (1993-1997, 1998-2002, 2003-2007, and 2008-2012) and also divided according to the following gestational ages: 22-27, 28-31, 32-36, and 37-43 weeks using the SPSS 19.0. Results: Perinatal mortality was reduced up to 72.3% during these years. The vast majority of stillbirths were in their 22-27 week of gestation. Almost half of the fetal deaths were caused by fetal abnormalities, while in 78% the placenta had a main or secondary role. A detailed description of embryo-membranes and clinical status of the mother was performed. Finally the authors identified 15 newborns who had reached the 28^th day of their life, of which 12 (80%) were premature. The majority were females and the mean age of the mothers was 28 years. Seven out of 12 newborns died of fetal problems, while three out of 12 due to intrapartum pathology. Conclusion: Pathogenesis of perinatal mortality is often unclear and associated to multiple causes. Impressive reduction of neonatal mortality has been realized during recent years due to the developments in obstetric and neonatal intensive care, but still many improvements are needed to be done.