Emergency department overcrowding is a growing problem worldwide including Rwanda. Literature shows that this problem has an impact on the functioning of the health care system and the quality of care provided. Research Methodology. This study aimed at exploring the phenomenon of overcrowding in ED/CHUK. Fifty one self-administered questionnaires were distributed to 40 ED nurses; these comprised three questions related to demographic data and 48 questions related to overcrowding. Correlation between overcrowding and causes and overcrowding with outcomes was explored and the pearson's test demonstrated that there is no linear correlation between these variables. Results. Findings from the demographic data demonstrated that the majority (92%) of ED nurse's were young (aged between 20 to 35 years). The majority (74%) of ED nurses had less than one to three years of experience in ED. With regard to overcrowding characteristics; nurses reported that the patient's waiting time for a physician varied between less than 30 min to more than 180 min; ED beds occupancy varied between 1 hour to more than 24 hours; patients were placed in the ED hallways for 1 hour to more than 24 hours; waiting room occupancy varied between less than 1 hour to more than 24 hours. Nurses attributed overcrowding to a variety of causes, including; a lack of inpatients beds (95%), large volume of trauma patients (87%), patients with no urgent condition (66), inappropriate referral of chronic cases (61 %), space limitation in emergency department (76%) and insufficient acuity ED beds (74%). Perceived outcomes (impact) were also multiples including, boarding patient in ED (92%), increased stress among nurses (79%), stress among physicians (60%), and risk of poor outcomes (60%), staff dissatisfaction (58%), violence between health care providers and patients (60%) and increased patient waiting time (58%). Regarding the undertaken interventions to reduce ED overcrowding, 100% of respondent asserted that there was some sporadic interventions, but not consistent. Recommendations: Like in other countries ED/CHUK overcrowding is a complex problem that needs to be addressed by all stakeholders: CHUK managers, hospital staff, ED staff, Rwandan district hospitals and Ministry of health. / Thesis (M.N.)-University of KwaZulu-Natal, Durban, 2008.