Levels of cyclic AMP and cyclic GMP in adult newt (Notophthalmus viridescens) intact and 22- and 35-day regenerate forelimbs were studied, as were the levels in the contralateral intact forelimbs and hind limbs. MS 222 anaesthetization results were compared with those of liquid nitrogen fixation. We observed an elevation in the levels of cAMP in animals having undergone MS 222 anaesthetization as compared with those immersed in liquid nitrogen. Cyclic GMP levels appear to be comparatively unaffected. Both the anaesthetic and liquid nitrogen animal series displayed differences in cAMP and cGMP levels according to the particular tissue sample taken and the stage of regeneration.