Diabetes insipidus is a rare but serious endocrine disorder. Paediatric patients were evaluated for polyuria at King Khalid University Hospital, Riyadh, Saudi Arabia, over a decade (2000–13). Relevant clinical examination and/or a triad of high serum osmolality, hypernatremia and low urine osmolality due to increased urine output confirmed the diagnosis. Water deprivation test was required in some cases with non-classic presentations. Appropriate brain imaging was performed whenever central diabetes insipidus (CDI) was suspected. Twenty-eight patients, 15 males (53.6%) and 13 females (46.4%), aged 0–17 years (mean: 6 years) were included. The calculated period prevalence was 7 in 10 000. In our cohort, 60.7% (17 of 28 patients) had CDI, 21.4% (6 of 28) were diagnosed with nephrogenic diabetes insipidus (NDI) and 17.9% (5 of 30) had psychogenic polydipsia. CDI was due to variable aetiology. Though CDI was the commonest, NDI was not a rare encounter in our community, possibly because of high consanguineous marriages.