The estimation of chronological age has been performed by various methods in forensic science. Among these, racemization methods, which are based on the age-dependent non-enzymatic changes of L-form amino acids to D-form mainly using aspartic acid, are one of the most reliable and accurate methods to date. Separation of enantiomers is generally performed by gas chromatography or high performance liquid chromatography. Various tissues with low metabolic rates have been applied for this purpose. In addition, single proteins purified from these target tissues are also applicable. In this brief review we describe this method in detail, noting points of caution, as well as the advantages and disadvantages of the different target tissues. In addition, special attention is given to the correlation rates obtained between chronological age and enantiomer ratios. Currently, based on accuracy of estimated age, simplicity of the method, time required, and reproducibility, tooth dentin is considered one of the best target tissues. Alternatively, analysis of osteocalcin and elastin have also provided accurate and reproducible results.