Background and Objectives: Parents' attachment is a strong and fundamental indicator in the formation of infant secure attachment and provides a model for the present-future emotional-social functioning. Since the unwanted pregnancy has harmful consequences for the health of the mother and the child and can affect the attachment of the parent to infant, this study was to determine the relationship between unwanted pregnancy and parental attachment in Ahvaz city. Methods: The sample consisted of 320 couple (320 mothers and 320 fathers) who have visited the healthcare centers for their 2 to 6-month-old infants. The data were collected through Muller (for mothers), Condon (for fathers), and demographic-reproductive questionnaires. Data analysis was conducted using SPSS version 24. Findings: According to the scores of two distinct questionnaires, the father attachment mean score in the group of unwanted was