Purpose: The purpose of this study was to investigate the learning effect of a standardized patient managed instruction program for a clinical maternity nursing course. Methods: The SP managed instruction was made for clinical cases in intrapartum and postpartum nursing care. The SP managed instruction was evaluated by using a quasi-experimental, nonequivalent control group post-test design with separate classes of students attending clinical maternity nursing classes at a nursing school in Incheon. Control groups were taught by traditional lecture/model method and experimental groups were taught by SP managed instruction. Data was collected from September 2009 to February 2010. Results: 1. There was no significant difference between the experimental group and control group in identifying relevant data (z=-1.418, p=.156) and necessary nursing skills performance (z=-.643, p=.520) for intrapartum nursing care. In addition, there was no significant difference between the two groups in identifying relevant data (z=-.264, p=.782) and necessary nursing skill (z=-.342, p=.732) for postpartum nursing care. 2. In clinical nursing skill performances the total score was statistically significantly higher in the experimental group than the control group (intrapartum care z=-4.181, p=.000, postpartum care z=-4.279, p=.000). 3. There was a statistically significant difference between the two groups (intrapartum care z=-3.731, p=.000, postpartum care z=-4.066, p=.000). Conclusion: In conclusion, the SP methodis effective in teaching clinical maternity nursing for student nurses and it is necessary to develop SP instruction courses for many areas in the clinical nursing education field.