Dissolved oxygen (DO) is essential for aerobic organisms and a critical driver of biogeochemical cycles. Low DO can lead to decreased biodiversity and altered ecosystem functions such as carbon metabolism and nutrient cycling. The frequency and severity of low-DO events are increasing in freshwater environments globally. Simultaneously, streams are experiencing changes in streamflow, driven by climate change or human water use, that accelerate drying-wetting cycles. Altered streamflow regimes, in particular the frequency of low-flow or pooled states, may lead to changes to DO behavior , such as increased variability in DO concentration and increases in the frequency and duration of hypoxia. In this study, we investigated hydrologic controls and their effects on DO in non-perennial streams - streams that dry at some point in time or space - across three contrasting regions of the continental USA. While diel patterns of DO in our focal streams were similar during lotic (i.e., flowing) states, DO responses (e.g., daily DO amplitude, daily minimum DO concentration) to drying varied among sites. Characterizing DO regimes is vital for management of both perennial and non-perennial streams and for understanding how flow-associated changes in DO may affect freshwater communities and ecosystem function.