The activity of glutamate-pyruvate transaminase (GPT) increases regularly as the fourth instar larva of Zabrotes subfasciatus develops into prepupa. On the other hand, glutamate-oxaloacetate transaminase (GOT) activity increases significantly (P < 0.05) during the first 12 hr, and then remains at a sufficiently constant level during the subsequent development of this larval instar except at 36 hr of development. However, at the time of prepupation, the GOT and GPT-activities show a decline, which is subsequently followed by an increase during the rest of the prepupal development. The activity of GOT is quite high during the early pupal life, i.e. up to 120 hr. On the other hand, GPT-activity falls significantly (P < 0.05) during the first 24 hr of pupal life and rise up to 120 hr during pupal development. Once again, in the late pupal development, the transaminases remain very active on account of the faster rate of histogenesis. During early adult life, the GOT and GPT are still active, as the early part of adult life of the insect is physiologically quite vigorous and accordingly the energy requirements of the body at this stage are intense. Subsequently, there occurs a regular attenuation of the activities of both of the transaminases in the aging bruchid.