BackgroundDelays in seeking timely appropriate care contributes to a large number of deaths from diarrhea in children. This study aimed to identify determinants of delays in seeking timely treatment by mothers/caregivers of under-five children with diarrheal diseases.MethodsWe used an unmatched case-control study from February—March 2017 among 316 children: 158 cases and 158 controls. Cases were mothers/caregivers with under-five children who had signs/symptoms of diarrhea and sought treatment after 24 hours onset of symptom. Controls sought treatment within 24 hours. Field workers collected data using a pre-tested standardized questionnaire. Multivariate logistic regression was conducted to identify determinants of delay in timely diarrhea treatment seeking. Statistical significance was declared by using a p-value<0.05 and 95% of confidence interval (CI) for an adjusted-odds ratio (AOR).ResultsThe determinants of delay in timely treatment seeking of mothers/caregivers of under-five children with diarrheal diseases were children <24months (AOR = 1.9,95%CI:1.1–3.4); fail to attend school (AOR = 2.4, 95%CI:1.2–4.6); being female children (AOR = 1.7,95%CI:1.05–2.9); preferring government health facility for the treatment of children with diarrheal diseases (AOR = 2.9, 95%CI, 1.3–6.7); lack of past history taking children to health facility and lack of counseling (AOR = 4.8, 95%CI:2.0–12.1); being in the15-25 years age (AOR = 1.7, 95%CI:1.1–3.0) and taking children to a health facility as a first response to diarrhea (AOR = 0.1, 95%CI:0.01–0.8).ConclusionsAge of the child, maternal age, and disease related determinants were determinants for seeking timely treatment to diarrheal diseases. Providing skilled based health education and counseling to mothers/caregivers on seeking timely treatment and taking children with diarrheal diseases to a health facility as a first response to diarrhea is a paramount intervention to reduce morbidity and mortality of children.