INTRODUCTION: Ketamine, at subanesthetic doses, produces psychotomimetic effects. In rodents, ketamine produces characteristic changes in oscillatory activity that can be recorded in local field potentials (LFP). One effect after systemic injection of ketamine is the emergence of abnormal high frequency oscillations (HFO) 130 ‑180 Hz that have been described in many rodent brain areas. Recently, we have shown that the olfactory bulb (OB) plays an important role in the generation of HFO after ketamine. AIM(S): The aim of the present study was to examine the extent to which nasal respiration may drive abnormal HFO after ketamine, in freely‑moving rats. METHOD(S): LFPs (from the OB) and nasal respiration (thermocouples implanted in the nares) were recorded before and after injection (saline or ketamine 20 mg/kg) from male Wistar rats. A separate group of rats was used to study nares blockade. To block the nares, rats were anesthetised and a silicon occluder was inserted into one or both nares. Controls were exposed to initial isoflurane for a comparable amount of time but without blockade. Rats were given recovery and then injected with ketamine. RESULTS: Ketamine immediately increased exploratory fast sniffing (4‑10 Hz), which correlated with increases in locomotor activity and HFO power. Saline injection did not substantially alter these measures. Nasal respiration entrained bursts of ketamine HFO recorded in the OB on a cycle‑by‑cycle basis. Further, ketamine-induced HFO was attenuated unilaterally by naris blockade on the same side. Bilateral naris blockade reduced power and frequency of HFO and also reduced hyperactivity produced by ketamine. CONCLUSIONS: Our results suggest that nasal respiration is a powerful drive of HFO after injection of ketamine in the OB. These findings may explain previous observations that ketamine-HFO couples to slower frequencies. Functional nasal respiration appears to be critical for the emergence of both HFO and hyperactivity produced by ketamine.