We report on age-dependent IDPN-effects in the rat. IDPN induces in rats irreversible movement disorders, which rise qualitatively and quantitatively with increasing age. IDPN-application causes a weight loss in rats, which correlates with the animals' ages. An equal IDPN-dose/kg body weight, in young rats (2 weeks old) causes only a temporary stagnation of the weight increase. Rats older than 2 weeks old suffer from a weight loss which rises with increasing age. In 7 months old rats, the weight loss amounts to as much as 50% of the weight at the start of the experiment. IDPN has an age-dependent strongly, deleterious effect on the rat eye (bleeding in the inner eye, buphthalmos with or without cataract) which finally leads to the loss of the eyes. If young animals (about 35 days old) receive the same IDPN-dose, these eye damages are essentially absent.