INTRODUCTION: In Haiti, childhood diarrhea is one of the leading causes of serious illness and death among children. Factors associated with medical treatment-seeking behaviours for diarrhea illnesses are poorly documented even though diarrhea treatment is key to reduce diarrhea-related child morbidity and mortality. To fill this gap, this study aimed to determine prevalence and identify factors associated with medical treatment-seeking behaviour for childhood diarrhea among Haitian mothers. METHODS: The study was based on secondary data, collected from the fifth round of the Haitian Demographic and Health Survey (HDHS 2016-2017). Medical treatment-seeking behaviour for childhood diarrhea was the outcome variable. Various demographic and socio-economic variables were considered as explanatory variables. Descriptive statistics (univariate and bivariate percentage distribution, Pearson's Chi-square test) and multilevel logistic regression were employed to draw inferences from the data. RESULTS: 1,245 children constituted our study population. The prevalence of children who suffered from diarrhea and received treatment (either oral rehydration solution (ORS) or recommended home fluids (RHF)) within two weeks period before the survey was 42.9% (95% CI 40.2-45.6). The results also revealed that children from the "Aire Métropolitaine de Port-au-Prince" region (Ref.), aged 12-23 months (aOR = 1.79; 95% CI: 1.26-2.55), whose mothers were aged 35 and above (aOR = 1.75; 95% CI: 1.15-2.67), whose mothers had secondary and higher levels (aOR = 1.63; 95% CI: 1.02-2.60), whose mothers were in a union (aOR = 2.18; 95% CI: 1.23-3.85), whose mothers did not consider the distance to the health facility a big problem (aOR = 1.35; 95% CI: 1.01-1.84), and children from communities with high access to improved toilet facilities (Ref.) were significantly more likely to receive diarrhea treatment. CONCLUSION: To increase the uptake of diarrhea treatment in Haiti, policymakers and stakeholders must give due consideration to those factors. They should educate the population on the causes of childhood diarrhea, its consequences, and the importance of ORS and RHF. The socio-economic vulnerability of some Haitian communities, especially those with low access to improved toilet facilities, could be a major barrier to the use of diarrhea treatments. Consequently, the Haitian government needs to subsidize these products so that they are freely available in public health facilities and pharmacies in these communities.