Several studies have linked Infertility associated spermatotoxicty/spermato-mutagenesis of Adult male Wister dietary exposed to aflatoxin B, the dynamics may be as a result of chromosomal aberration or simply by its anti-spermatogenesis properties. To evaluate the protein composition of epididymal fluid and sperm extracts of the rats using a two-dimensional gel electrophoresis. Epididymal luminal fluid from the corpus and cauda regions of male animals rendered infertile by the anti spermal and mutagenic properties of aflatoxin B1 possessed a certain protein (contraception-associated protein 1, CAP1) which has a molecular mass of - 25 kDa and isoelectric point (pl) of 5.8; although it wasn’t found in fluids, but was present in sperm, from fertile rats. Infrared matrix-assisted laser desorption/ionization mass spectrometry indicated that the molecular mass of CAP1 was 20 420 ± 120 daltons. Homology of the hormone from a known insect (Acheta domesticus) was carried out by analysing 17 amino acids which demonstrated 49 percentile homologous linkage Silver-recolored gels demonstrated the nearness of CAP1 in more prominent sums in cauda than in corpus liquid from the dietary uncovered creatures, while liquid from the rete testis needed CAP1. In vitro hatching periods of tissue from the caput, corpus, and cauda epididymidal areas with [35S] methionine gave no insight that CAP1 was a discharge result of the epididymal epithelium. The nonattendance of CAP1 from luminal liquid acquired from the sperm-drained corpus epididymidis of the dietary uncovered rats recommended this had a spermatozoa root. CAP1 was available in spermatozoa from the caput epididymidis however not from the rete testis in control creatures. less CAP1 was available in cleanser concentrates of cauda sperm from the dietary uncovered rats than in sperm from control creatures, proposing against spermatogenesis related dislodging of protein from sperm to liquid. The nearness of CAP1 in epididymal liquid, presumably beginning from spermatozoa, proposes that aflatoxin B1 initiate barrenness by a pre-previous protein in preparation.