The effects of three retinoids, all-trans-retinoic acid (all-trans-RA), 13-cis-RA, and etretin were examined on mRNA abundance of nuclear retinoic acid receptors (RAR-alpha, beta, and gamma) in lung and liver of retinol deficient and chow fed rats. All-trans-RA increased lung RAR-beta mRNA levels 5 or 11-fold in chow fed and retinol deficient rats, respectively. Similarly to lung, liver RAR-beta mRNA levels were 3-fold higher in retinol deficient rats fed all-trans-RA than the rats fed cottonseed oil. Lung RAR-gamma mRNA levels were also induced 2-fold by all-trans-RA. In contrast to this, 13-cis-RA and etretin at equimolar doses failed to enhance lung or liver RAR-beta or lung RAR-gamma mRNA levels in retinol deficient rats. These data for the first time show that all-trans-RA is more effective than its 13-cis-isomer in regulating the expression of RAR-beta and gamma transcripts in adult animal.