To investigate the influence of the wars in Croatia and Bosnia and Herzegovina on incidence and perinatal outcome of singleton preterm births at the Department of Gynecology and Obstetrics in the Split University Hospital. Data were collected by reviewing patients’ files at the Department of Gynecology and Obstetrics from three periods: the three years before the war (1988–1990), during the war (1992–1994), and after the war (1996–1998). A total of 2,358 patients’ files of singleton preterm delivery were analyzed. Singleton preterm delivery rate decreased during the war (5.02%) and post-war period (4.74%) compared to the pre-war period (6.19%). Stillbirth and early neonatal mortality rates of singleton premature babies significantly increased during the war to 226%, compared to 193% before the war and 134% after the war. Early neonatal mortality rate was 215% during the war, 209% in the pre-war period, and 156% after the war. Despite the continuous decrease in singleton preterm birth rate throughout the observed periods, the increase in stillbirth rate and early neonatal mortality rate during the war might have been caused by the war. This may be due to primary gynecological care being inadequate for many pregnant women.