Expression of 25 mRNAs in a single human lymphocyte was investigated using the reverse transcription nested polymerase chain reaction (RT nested PCR) method. Proteins corresponding to the mRNA investigated were mucin antigen, melanoma antigen, pregnancy-specific beta-1 glycoprotein 4, phenylethanolamine-N-methyl-transferase, beta B3-crystallin, homeobox 4A, interleukin 2, cluster of differentiation 8, progesterone receptor, parathyroid hormone, gastrin, cholecystokinin/pancreozymin, glucagon, insulin, enkephalin, thyroid stimulating hormone, adrenocorticotropic hormone, synapsin I, immunoglobulin (Ig)M, IgD, IgG1, IgG3, IgE, IgA, and T cell receptor alpha. All mRNAs were detected in single lymphocytes of two individuals, without exception. In addition, transcripts of IgM, IgD, IgG1, IgG3, IgE, IgA, and the T cell receptor a gene were detected in single sperms. The results strongly suggest the possibility that all mRNAs may be expressed in a single human cell, of both somatic and germ lineage. Thus, cells can consume energy in vain to produce functionally meaningless gene transcripts. However, this basal or illegitimate transcription may be essential for the birth of living matter: the arrow of time in a cell. Moreover, the phenomenon implies the potential of using lymphocytes in place of inaccessible tissue for the diagnosis of genetic diseases.