Conditional self-discrimination is the learned ability that animals have shown to discriminate aspects of the individual, such as their own behavior, their own internal states or their own image. This concept corresponds to the behavioral version of self-awareness. Some authors suggest that this process have a phylogenetic course and depends on the social structure of the species. However, we have not detected research on its ontogenetic course. This study aimed to explore experimentally the relationship between age and the acquisition of conditional self-discrimination. In particular, a matching-to-sample experimental paradigm of conditional discrimination of the spatial orientation of the own behavior in rats was developed in a symmetric Y-maze. This type of labyrinth allows controlling external keys of spatial orientation, in addition to allow sequences of trials followed without the intervention of the experimenter. A first pilot study was conducted with eight adult subjects of the Wistar strain (weeks 19 to 32 of age) and, subsequently, the experimental study was carried out with the four young subjects (weeks 7 to 23 of age). Comparison stimuli associated with spatial orientation of the own behavior ("previous turn to the left" vs. "previous turn to the right") were geometric figures (triangle vs. circle) of yellow color on a black background. Discrimination index required to demonstrate acquisition was 0.8 in at least one trial. In the pilot study, six of eight adult subjects achieved the required level, while, in the experimental group, three of four young subjects achieved the criterion. Although both groups showed a tendency to acquire conditional self-discrimination, the acquisition rhythms were different according to age, consistent with the inverted U hypothesis of the ontogeny of learning, that is: younger subjects learn more slowly than adult ones. However, to complete the test of such hypothesis, an additional study is required with older subjects. Our ontogenetic findings complement the comparative studies of animal self-awareness, which give clues of the phylogeny of this process.