Dissertation (MSc Midwifery)Puerperal sepsis is an infection of the genital tract which happens at any time since the break of membranes, during labor, and within 42 days post-delivery. Knowledge and good hygienic practice of post-delivery women are important for the prevention of puerperal sepsis. This study aimed to assess knowledge and practice on prevention of puerperal sepsis and their determinants among post–delivered women and nurse midwives Dar es Salaam region. A hospital-based Analytical cross-sectional study was conducted including 343 post-delivery women and 120 nurse midwives, from 11 February to 19 March- 2021 in three districts hospital and 5 health centers in the Dar es Salaam region. Data were collected using self-administered questions. Determinants of knowledge and self-care reported practice was determined using binary logistic regression. Multivariate analysis was done to control all other variables. SPSS version 23.0 was used for data analysis, P-value of less than 0.05 was considered significant. The study revealed that more than half of post-delivery women 213 (62.1%) had adequate knowledge on prevention of puerperal sepsis and only 39 (11.4%) had good self-care practice on prevention of puerperal sepsis. Post–delivered women with secondary education (AOR = 2.84, 95% CI = 1.68-3 .30, p = 0.001), college/university (AOR = 5.59, 95% CI = 2.07-5.80, p = 0.001), and who receive information from HCWs (AOR = 1.06, 95% CI = 0.55-2.06, p = 0.049), were significant determinants for post-delivery women knowledge on prevention of puerperal sepsis. Secondary education (AOR = 1.44, 95% CI = 0.52-4.005, p = 0.001), college (AOR = 9.29, 95% CI = 2.36-10.14, p = 0.001) and >4 ANC visit (AOR = 1.21, 95% CI = 0.49-2.27, P = 0.032) were determinants for self-care reported practice on prevention of puerperal sepsis. More than half of nurse-midwives 66 (55%) had adequate knowledge on the prevention of puerperal sepsis, and 48 (40%) had a good practice on prevention of puerperal sepsis. Nurse-midwives with diploma in nursing (AOR = 2.66, 95% CI = 1.54-2.77, p = 0.031), bachelor in nursing (AOR = 5.98, 95% CI = 1.93-6.55, P = 0.009), in-service training (AOR = 2.44, 95% CI = 1.22-2.98, P= 0.008) and availability of guidelines (AOR = 1.76, 95% CI = 0.01-2.28, P = 0.027), were significant determinants for nurse- midwives knowledge on prevention of puerperal sepsis, working experience 4-10 years, (AOR =1.06, 95% CI = 0.01-1.71, p = 0.025), >10years (AOR =4.03, 95% CI = 2.07-4.17 , p = 0.001), in-service training (AOR = 6.98, 95% CI = 1.22-7.94, p = 0.029) and availability of equipment (AOR = 7.41, 95% CI = 1.49-7.94 , p = 0.014), were determinants for nurse midwives practice on prevention of puerperal sepsis. According to the study knowledge of post-delivery women does not influence the self-care reported practice among post-delivery women. And for nurse midwives knowledge also does not influences practice for nurse midwives on prevention of puerperal sepsis. (AOR =1.23, 95% CI = 1.94-3.34, p = 0.33). Significant gap in self-care reported practice among post-delivery women regarding puerperal sepsis was evident. Special attention should be given to women with low income, low education levels, and those with inadequate ANC utilization. Nurse-midwives knowledge and practice in puerperal sepsis need to be improved, successful implementation of infection control measures in maternity units particularly in puerperal sepsis prevention, well-structured continuing education, and in-service training programs are the substantial elements that would improve nurse-midwives knowledge and practice regarding prevention of puerperal sepsis.