Dissertation (MSc Nursing Education)Background: Raising awareness of women about obstetric danger signs would improve the early detection of problems and seeking timely obstetric care. This study aimed to determine the association between antenatal attendance and knowledge on obstetric danger signs among postnatal mothers in Zanzibar. Method: It was a community-based cross-section study. A multistage sampling technique was used to select study participants that were postnatal mothers from day 0 up to 42 days. Sample size was 330. Data were collected using structured questionnaires and using SPSS version 25 software for analysis. Descriptive analysis and chi square test were done for establishing a relationship and p value < 0.05 has been considered as significant. Binary Logistic regression analysis both odds ratio (OR) and adjusted odds ratio (AOR) was used to determine the strength of association Results: Only 85 (23.64%)had adequate knowledge on obstetric danger signs, during pregnancy45 (13.64%), labor162 (49.09%), postnatal 90 (33.03%) and neonatal danger signs 75 (20.30%).Majority 88(26.67%) of post-natal mothers were aged less than 35years.Going on the antenatal use, 61.52% of study participants had sufficient antenatal visits. There was a significant association between antenatal attendance and knowledge on obstetric danger signs. Postnatal mothers who had sufficient antenatal visits were 3 times more likely to have adequate knowledge compared with the postnatal women who had insufficient antenatal visits (AOR=3.612, 95% CI=2.209 -5.906; p< 0.001). Conclusion: A significant proportion of postnatal mothers in Zanzibar showed inadequate knowledge on obstetric danger signs. Antenatal attendance was sufficient but knowledge on obstetric danger signs was inadequate. High number of ANC visit predicted higher knowledge on obstetric danger signs.