Background: Labor is an event and experience in a woman's life. After giving birth, a mother experiences a postpartum period or puerperal period that is a recovery period. In this time, there are many physical and psychological changes that make uncomfortable. Uncomfortable feeling can cause anxiety, especially in primiparous mothers. Therefore,  not to have an impact rise in stress, even untill postpartum depression, a midwife as a spearhead of provider maternal health care must be able to reduce the anxiety which experiences of postpartum mothers, especially primiparous through assistance ‘OSOC’ methods. The methods starting from pregnancy, childbirth, postpartum, newborn baby until selection of Family Planning method, so the health of mother and baby can be better.

Objective: To determine the effect of the application of the OSOC assistance maternity service model toward anxiety among primiparous mothers in the postpartum period at Kendal District Health Center.

Research Methods: Quantitative data analysis was used to assess the anxiety of postpartum primiparous mothers with the intervention group and the control group, a type of Quasi Experiment research with a non-equivalent control group design. The subjects of this research was divided into two groups, they were intervention groups and control groups. In the intervention group, it was given in the form of providing OSOC assistance in the postpartum period, while the control group was given conventional puerperal care. The research site was conducted at  Kendal District Health Center in May-October 2019.

Results: There was a significant difference between