This paper reviews experimental work bearing on the feasibility of using the analog of glucose, 5-thio-D-glucose, to control human male fertility. The initial experiments in mice indicated that suitable oral doses of thioglucose caused reversible infertility unaccompanied by loss of libido or evidence of extratesticular toxicity. Subsequent work in mice and rats showed that treatment of 7 or 8 weeks appeared to cause irreversible sterility in many of the animals. In both species the smallest doses causing infertility also caused transient hyperglycemia. In rats a large dose of thioglucose was found to raise the concentration of nonesterified fatty acids in the blood and repeated smaller doses increased the excretion of catecholamines. These reports, suggesting that it can cause sterility and has extratesticular effects on metabolism, do not augur well for the acceptibility of thioglucose as a suitable chemical with which to control fertility in the human male.