The state of fusion of the basilar synchondrosis (spheno-occipital fissure) has been advocated as a good age indicator. In most anatomy textbooks, the fissure is described as "open" throughout childhood and puberty, and its fusion indicates the beginning of adulthood. This last assertion has been disputed by some researchers who contend that the synchondrosis fuses during the adolescent period around 10-14 years old. In the current study, the stage of closure of the fissure was established for 92 cadavers after stripping the dura mater completely from the surface of the endocranium between the rostral margin of the foramen magnum through the body of the sphenoid bone and the clinoid anterior processes. The fissure was classified either "open" or "closed" according to the presence or absence of cartilage as viewed on the endocranium. In the male sample (n=70) no correlation was detected between chronological age and the time of closure of the synchondrosis. The mean age of the group of individuals with "closed" synchondrosis (16.9 years old) was almost the same as that of the group with "open" synchondrosis (15.7 years old). These findings seem to suggest that the high variability in the age of fusion of the basilar synchondrosis would preclude a reliable age estimation based solely on the stage of fusion of the basilar suture, especially when the questioned remains pertain to the forensic realm. In the female sample (n=21), on the other hand, there were significant differences in age between the subgroups with "open" and "closed" spheno-occipital fissure. The mean age of the group with "open" synchondrosis was 12.3 years old, and the group of individuals with "closed" synchondrosis had a mean age of 15.7 years old. Although these findings are statistically significant, the sample size was rather small. Should these results be corroborated in further investigations, it could be advocated that the stage of the fusion of the basilar synchondrosis is a reliable indicator of age in female individuals. 3 tables, 4 figures, and 31 references