Background/Aims Health education for postnatal women after discharge is essential to informing women about nursing infants, self-care, identifying danger signs, therapy, medication and family planning intention. The aim of this study was to examine health education and health promotional messages given to women in the postnatal wards of Kenyatta National Hospital. Methods This descriptive cross-sectional design study was carried out with 105 postnatal women at the Kenyatta National Hospital, Kenya. A semi-structured questionnaire was used to collect data on women's postnatal care knowledge, and the timing and delivery of health education messages. Results The participants were knowledgeable about a number of postnatal care practices but lacking in some areas. Most received information on postnatal care immediately after birth. Healthcare professionals, including nurses, midwives, doctors and nutritionists, were the leading source of information. Health messages were shared in Kiswahili or a mixture of English and Kiswahili. The majority of participants reported they were able to understand the health messages they received. Conclusions Postnatal women were knowledgeable about postnatal care practices, although gaps in their knowledge were evident in some areas. Nurses and midwives working in obstetric wards need to initiate postnatal health education before discharge from the hospital to avoid delays in communicating crucial health messages and ensure that women are adequately informed.