The effect of the ketogenic diet on behavior and cognition is unclear. We addressed this issue in rats behaviorally and electrophysiologically. We fed postnatal day 21 rats a standard diet (SD), ketogenic diet (KD), or calorie-restricted diet (CR) for 2–3 weeks. CR controlled for the slower weight gain experienced by KD-fed rats. We assessed behavioral performance with a locomotor activity and a conditioned fear test. To evaluate possible parallel effects of diet on synaptic function, we examined paired-pulse modulation (PPM) and long-term potentiation (LTP) in the medial perforant path in vivo. KD-fed rats performed similarly to SD-fed rats on the behavioral tests and electrophysiologic assays. These data suggest that the KD does not alter behavioral performance or synaptic plasticity.