In recent years postnatal depression (PND) has become one of the most important public health issues because of its prevalence. Estimates for those affected by PND suggest a range of 10–15% of new mothers worldwide. In the context of Saudi society, attitudes toward this disorder are influenced by various beliefs, traditions, cultural factors, and values. These variables trigger considerable disparity in terms of frequency of symptoms. The symptoms of postnatal depression vary and can arise over a period of months, causing profound effects on mothers, also effecting mother-baby and broader familial relationships. The current study establishes the rate of occurrence and risk factors for PND in the western region of Saudi Arabia, to build on existing data. In total, 217 new Saudi mothers were recruited and data was collected using the Edinburgh Postnatal Scale (EPDS) in conjunction with a self-report questionnaire. Based on recommendations in previous studies, an EPND cut-off point of 13 ≥ was applied herein. Findings show the prevalence of PND, approximately 17.1% among the participants, and contributing factors included a previous history of depression, χ2 = 67.74, df = 1, p < .05, problems with the child’s health, χ2 = 31.42, df = 1, p < .05, issues with home support, χ2 = 43.47, df = 1, p < .05, and pregnancy complications, χ2 = 7.19, df = 1, p < .05. Meanwhile, no correlation was found between PND and the baby’s gender, delivery type, breastfeeding, mother’s age, or mother’s educational level. Additional studies are required to confirm these findings, and to identify other risk factors.