Preterm labor is the main cause of infants' death, and the main reason for undesirable consequences of pregnancy which still occur in some births, despite all of the interventions in this regard. The aim of this study was to evaluate every preterm birth and determine its maternal risk factors in Hormozgan province in 2013.This case-control study was conducted in 2013 on the health and hospital records of 735 pregnant mothers with preterm labor (20-37 weeks) which were located in Bandar Abbas in southeast Iran. The sampling method would be multi-stage cluster sampling. The data collecting tool was a valid questionnaire by the Iran Ministry of Health and Medical Education, which included 5 components (demographic information, checking the current pregnancy of the mother, the maternal factors related to preterm labor in the previous pregnancy, evaluating the fetal factors associated with preterm labor in the current pregnancy and other additional information related to the factors associated with prematurity). Data were analyzed using descriptive statistics, regression and Chi-square tests.The prevalence of preterm labor in Hormozgan province in 2013 was 5.5%. In our study and among the effective factors on preterm labor, revealed genital-urinary tract infections during pregnancy were (35.8%), PROM (30.3%), history of abortion (19.9%) and unplanned pregnancy (18.1%) in between pregnant women with preterm labor. Our study showed that most mothers had delivered in 33 to 37 weeks among the mothers who had preterm labor in 2013 (75%) and the statistic of very preterm labor (less than 32 weeks) in Hormozgan was 5%.Identification of the prevalence and associated factors with preterm labor can reduce the mortality rate and infants' complications of it in addition to help find a way to prevent this problem.