In this paper the present status of insect chemosterilants is reviewed. Chemosterilants may be categorised into eight main chemical groups. Practical control measures involving the use of chemosterilants are discussed, also the persistence of these substances when applied to the insect. The gross effects of chemosterilants on insect reproductive systems and also the effects on egg develpment when female insects are mated to chemosterilised males are described, including dominant lethality, reciprocal translocation, enzyme inhibition and sperm inactivation. The possibilities of recovery of fertility and insect resistance to the sterilising effects of chemosterilants are discussed. Endocrine misfunction and chemosterilant action are related. The only practical chemosterilants as control agents are the aziridines although mutagenic hazards associated with these substances preclude their widespread usage. The sterilising activity of certain insect hormone analogues and related substances encourages the belief that safe insect specific sterilising agents can be found.