BackgroundTanzania has made a significant improvement in wasting and underweight indicators. However, stunting has remained persistently higher and varying between regions. We analyzed Tanzania Demographic and Health Survey (TDHS) datasets to examine (i) the trend of stunting over the period of 25 years in Tanzania and (ii) the remaining challenges and factors associated with stunting in the country.MethodsThis secondary data analysis included six TDHS datasets with data of 37,409 under-five children spreading in 1991–1992(n = 6587), 1996(n = 5437), 1999(n = 2556), 2004–05(n = 7231), 2009–10(n = 6597), and 2015–16(n = 9001) conducted in all regions of Tanzania. Variables specific to children and their caregivers were analyzed using SPSS version 22. The variables considered include child anthropometric variables, caregiver’s demographic characteristics and household’s socio-economic factors. We used frequencies and percentages to compare stunting prevalence across the six surveys and chi-square test and three-level hierarchical logistic regression to examine the factors associated with stunting also applying sample weighting as advised by TDHS.ResultsThe prevalence of stunting has declined by 30% over the period of 25 years in Tanzania. However, one in three children aged below five years remains stunted with overweight and obesity more than doubled (from 11 to 25%) in the same period among women of reproductive age. The factors associated with stunting included children living in female-headed households (AOR = 1.16, P = 0.014), aged 24–35 months (AOR = 1.75, P = 0.019), born with low birth weight (AOR = 2.14, P < 0.001) and with inconsistent or without breastfeeding (AOR = 3.46, P < 0.001 and AOR = 4.29, P = 0.001) respectively. The risk of stunting among children living in urban area (AOR = 0.56, P < 0.001), with higher caregiver’s education (AOR = 0.56, P = 0.018), obese mother (AOR = 0.63, P < 0.001), households with highest wealth index (AOR = 0.42, P < 0.001), and among girls (AOR = 0.77, P < 0.001).ConclusionsThe burden of stunting in Tanzania has declined by 30% in the past 25 years, but still affecting one in every three children. Efforts are needed to increase the pace of stunting decline especially among boys, children in rural areas, from poor, uneducated, and female-headed households, and through improving infant and young feeding practices. Effective and tailored nutrition-sensitive and specific interventions using multisectoral approaches should be considered to address these important determinants.