Spiroindoline derivatives, process for their preparation and pharmaceutical compositions thereof, their use for the treatment and/or prophylaxis of diseases, and their use for the manufacture of medicaments for the treatment and/or prophylaxis of diseases, especially sex-hormone-related diseases in both men and women, in particularly those selected from the group of endometriosis, uterine fibroids, polycystic ovarian disease, hirsutism, precocious puberty, gonadal steroid-dependent neoplasia such as cancers of the prostate, breast and ovary, gonadotrope pituitary adenomas, sleep apnea, irritable bowel syndrome, premenstrual syndrome, benign prostatic hypertrophy, contraception and infertility (e.g., assisted reproductive therapy such as in vitro fertilization). The present application relates in particular to spiroindoline derivatives as gonadotropin-releasing hormone (GnRH) receptor antagonists.