The objective of this study was to determine the causes of rejection to intrauterine device postpartum (IDP) in puerperal patients before they left the hospital. Two hundred puerperal patients who accepted IDP and two hundred patients who rejected IDP were studied. They received a questionaire to know the motives to accept or not IDP and degree of knowledge about it. There was not statistical differences between groups in relation to age, scholarity, religion, marital status, occupation and degree of knowledge, 51% had prenatal control, 62% of puerperal patients who rejected IDP did not have information about this contraceptive method, in 17% husband did not accept it and 9.5% have been influenced by negative rumors about IDP. In conclusion puerperal patients reject IDP mainly for lack of knowledge in relation to IDP and because their husbands did not accept it.