ABSTRACTDiarrhoeal diseases are major causes of morbidity and mortality among under-fived-aged children globally. In Nigeria, 10% of under-five deaths in 2016 were due to diarrhoea. The diseases were responsible for 9% of childhood deaths in Lagos State in 2011. This study examined the spatial pattern and sociodemographic, environmental, hygiene and behavioural factors associated with diarrhoeal morbidity in Lagos State. Data on reported cases of childhood diarrhoeal diseases in government hospitals was analysed using spatial statistical techniques. Data from 2013 Nigerian Demographic Health Survey was used to determine diarrhoeal disease risk factors through multivariate logistic regression analysis. Lagos Island recorded the highest (34.2%) number of cases, followed by Agege (16.6%) and Somolu (13.2%) local government areas (LGAs). The spatial distribution of diarrhoeal cases is random. The prevalence of diarrhoeal diseases during the two-week period before the survey was 7.5%. Factors significantly associated with diarrhoeal disease morbidity were child’s age, mother’s age, religion, paternal education and occupation, mother’s occupation, source of drinking water, floor material, mixed feeding and mothers not wanting the last child. These findings highlight the need to strengthen the provision of safe water supply. Educational programmes that emphasise treatment of drinking water, safe hygiene and sanitation practices should be implemented.