Background: Health education plays a crucial role in enhancing knowledge and shaping positive
attitudes toward sexually transmitted diseases, especially among primigravida women. Achieving this
requires an effective instructional system design model tailored to the needs of the target group. Aim
of the research: Was to evaluate the effect of an instructional system design model on knowledge
and attitude regarding sexual transmitted disease among primigravida women. Research design: A
quasi-experimental design was used to conduct this study. Research Setting: Primary health care
unit at Sendbes in El-Qanater Al-Khairiya, Qalyubia Governorate. Sampling: A purposive sample of
115 primigravida women who fulfill inclusion criteria were included in the study. Tools of data
collection: Three tools were used for data collection; I) Structured interviewing questionnaire, II)
Knowledge assessment questionnaire and III) Pregnant women attitude questionnaires. Results:
Showed highly statistically significant improvements in all items of knowledge post implementation
of instructional system design model (P