Background
Diarrhea is second only to pneumonia as the cause of child mortality worldwide. Developing countries particularly in Sub Saharan Africa including Ethiopia have a high burden of this disease. Studies showed that different factors were associated with the occurrence of childhood diarrhea. Therefore, this study was aimed to identify determinant factors of diarrhea in underfive children in Benishangul Gumuz Regional State, western Ethiopia.

Method
Demographic and Health Survey (DHS) data of 2011 was used for this study. The data was extracted from the National DHS data using data extraction tools. A total of 925 under five children were selected. The logistic regression model was employed to examine the determinants of childhood diarrhoea. Both bivariate and multivariate data analysis was performed using SPSS version 16.0.

Result
The results of this study indicated that low level of maternal education [AOR?=?1.81, 95% CI (1.12,2.76)], absence of toilet facility [AOR?=?3.5, 95% CI (2.4, 5.2)], improper child stool disposal methods [AOR?=?2.05, 95%CI (1.36, 3.10)], having more than two under five children [AOR?=?1.73, 95% CI (1.03, 2.93)], higher birth order [AOR?=?6.1, 95% CI (3.1,12.2)] and the age of children [AOR?=?1.9, 95% CI (1.2, 3.6)] were found to be the risk factors for childhood diarrhea after adjusting for other variables. When toilet facility was stratified by maternal education, it showed that children of mothers who had no education were the most vulnerable in the absence of toilet facilities [OR?=?9.16, 95% CI (5.79, 14.48)].

Conclusion
Under poor environmental conditions, mothers with primary education and above protected their children against diarrhea better than mothers with no education. Thus, implementing effective educational programs that emphasize environmental health and sanitation practices and encouraging female school enrolment would reduce childhood diarrheal morbidity in the region.