Weanling, male and female, stroke-prone, spontaneously hypertensive rats (SP/SHR) were fed either a regular diet, a low protein diet derived from fish tissue + 1% saline drinking water, or the fish diet + 1% saline + daily injections of 0.1 mg Enovid/100 g bw/sc. After 48 days, the Enovid-treated animals developed acute and lethal strokes characterized by massive thrombonecrogenic lesions of the parietal lobe. The blood pressure of the Enovid-treated SP/SHR rose most acutely. The low protein fish diet was markedly catabolic and caused hyperlipidemia, hyperglycemia, elevated ACTH and beta-endorphin levels concomitant with reduced gonadotrophic function. Treatment with Enovid caused severe exacerbation of all of the foregoing changes. It is proposed that a low protein fish diet + 1% saline will accelerate the appearance of strokes in SP/SHR and that Enovid will enhance this effect through its anti-gonadotrophic activity and ability to stimulate increased pituitary-adrenal secretion.