The effects of flow pattern on the breakup length of circular air-assisted water jets are investigated by varying, independently from other flow parameters, the air-water flow patterns within small diameter tubes. A Y-type mixer and a coaxial needle-type mixer are used to generate air-assisted jets. Maps of the flow pattern transitions are presented using both mixer types. Liquid-only and air-assisted jets in the Rayleigh and first wind-induced breakup regimes are observed. Bubbly, bubbly-slug, slug, and slug-annular flow patterns are observed. Disperse-bubbly flow is shown to result in longer jet breakup length when compared to other flow patterns having the same flow parameters. High-speed visualization of jet breakup reveals how the flow pattern influences the dominant jet breakup mechanism. Linear jet stability is used to predict the jet breakup length based on the liquid Weber number, Ohnesorge number, and volumetric void fraction when the flow pattern is disperse-bubbly and bubbly-slug.