In Experiment 1, Long-Evans rat pups received medial prefrontal cortex (PFC) aspirations or sham surgery on Postnatal Day 10 (PND 10) and were then trained on PND 23 to perform one of two T-maze tasks: discrete-trials delayed alternation (DA) or simple position discrimination. Early PFC damage produced a selective failure to learn the DA task. Experiment 2, pups given the same lesion or sham surgery were trained on DA on PND 19, PND 27, or PND 33. In relation to sham-operated controls, pups with PFC damage were impaired on PND 19, somewhat impaired on PND 27, and entirely unimpaired when tested on PND 33. In Experiment 3, pups given larger lesions of the frontal cortex on PND 10 were impaired on DA when tested on PND 23 but not when tested on PND 33. These findings indicate that early PFC lesions result in a memory deficit around the time of weaning, which then recovers over the next 10-14 days of development. Moreover, the early deficit is selective for a late developing cognitive process (or processes) that is involved in acquisition of DA.