Background: Maternal-infant attachment (MIA) is a critical part of the foundation for a healthy life. Therefore, factors related to MIA are necessary to the natural development of the child. Objectives: The present study aimed at identifying factors associated with MIA. Methods: This systematic review has been developed based on the PRISMA checklist. The researchers conducted this study using English databases (Web of Science, HSRProj, CINAHL, MEDLINE, HMIC, NCJRS, Child Data, IBSS) for English related documents and Persian databases (SID, Magiran, Iran Medex, Google Scholar and Iran Doc) for Persian related documents, from August 1990 to May 2018. Results: Out of 137 published documents, 27 studies met the inclusion criteria. Factors influencing MIA were divided to two categories: Maternal factors (age, education level, job, income, place of residence, psychosocial support, marital satisfaction, psychological disorders, single parenting, number of children, number of pregnancies, unplanned pregnancy, high risk pregnancy, level of attachment to the fetus during pregnancy, type of delivery, educational attainment, rooming-in, skin-to-skin contact, effective communication, mother's perceptions of her infant, involvement in caring for the newborn, early initiation of breastfeeding, and oxytocin concentration) and infancy factors (health problems, prematurity, infant gender, and infancy moods). Conclusions: Guided by the study results it could be elaborated that MIA is significantly associated with several maternal and infantrelated factors. In light of the study results, it is recommended that health care providers should assess mothers and their infants for their attachment behaviors and allocate more time to educate them about the attachment process and how to accomplish it.