Abstract: The present invention relates to methods for categorizing samples containing spermatozoa by obtaining a RNA profile in said sample by hybridization and/or sequencing techniques, wherein the RNA is preferably selected from messenger RNA (mRNA), noncoding RNA (ncRNA) and micro RNA (miRNA). The present invention relates further to the use of RNA profiles and/or translation product profiles as selection criterions, such as fertility and breeding selection, of the sample donor. The present invention allows for distinguishing male and female spermatozoa of a sample and subsequently separating male and female spermatozoa. With the methods of the invention categorized samples as well as male and female spermatozoa can be obtained.