Adult female and male Imp: DAK rats were exposed beneath a real VDU screen (Erl groups) loaded with light-green characteristics due to computation of trigonometric functions in a loop program from a microcomputer. The control animals were exposed beneath a sham screen (Esh groups), being the front glass of vacuum devoid cathode ray tube covered with a transparent celluloid sheet printed with light-green characteristics. The difference in body weight of foetuses from autopsied Erl and Esh females was due mainly to a one-day delay in the fecundation of Esh females. In other groups of Erl females, a prolongation of the oestrous cycle was found in comparison to that of the Esh females. In both Erl females and Erl males, a nonsignificant decrease of weight of anterior pituitary and adrenals was found. RNA quantity was augmented in the anterior pituitary of Erl females and DNA quantity was diminished in the hypothalamus of Erl males. The obtained results suggest the suppression of hypothalamo-hypophyseal function in rats exposed to a real VDU screen.