Sleep supports the consolidation of declarative memory in children and adults. However, it is unclear whether sleep improves odor memory in children as well as adults. Thirty healthy children (mean age of 10.6, ranging from 8–12 yrs.) and 30 healthy adults (mean age of 25.4, ranging from 20–30 yrs.) participated in an incidental odor recognition paradigm. While learning of 10 target odorants took place in the evening and retrieval (10 target and 10 distractor odorants) the next morning in the sleep groups (adults: n = 15, children: n = 15), the time schedule was vice versa in the wake groups (n = 15 each). During encoding, adults rated odors as being more familiar. After the retention interval, adult participants of the sleep group recognized odors better than adults in the wake group. While children in the wake group showed memory performance comparable to the adult wake group, the children sleep group performed worse than adult and children wake groups. Correlations between memory performance and familiarity ratings during encoding indicate that pre-experiences might be critical in determining whether sleep improves or worsens memory consolidation.