Stunting is among the barriers constraining growth and development of many underfive years children particularly in developing countries like Tanzania. Rukwa is among the regions with highest prevalence rate of stunting of the underfive children. Water, sanitation and hygiene (WASH) practices may contribute on stunting of underfive children in the region. The main objective of the study was to explore WASH practices influencing stunting among underfive children in Rukwa Region. A cross-sectional survey design was used to collect data from households whereby 401 mothers with children aged 6-59 months were selected by using simple random sampling. This study used raw data collected through questionnaire by Tanzania Demographic and Health Survey (TDHS) 2015/16. Data analysis was done descriptively and using logit regression model. STATA version 14 was employed to run the analysis. Results showed that spending short time in fetching water for a mother (AOR=0.468, p=0.021) as water practice, and household members use of improved toilet (AOR=0.442, p=0.041) as hygiene practice had significant influence on stunting of underfive children as the two WASH practices minimize the likelihood of stunting. The study recommends that policy makers should endorse new policies or review existing ones as well as implement most appropriate interventions which can improve household access to water and promote sanitation and hygiene especially by providing adequate clean and safe water while sensitising an improvement and use of toilets among community members so as to reverse the rate of stunting partly contributed by poor WASH practices in Rukwa Region.