The present invention relates to indolinone derivatives substituted in the 6 position of general formula ##STR00001## wherein R.sub.1 to R.sub.6 and X are defined as in claim 1, the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof, particularly the physiologically acceptable salts thereof, which have valuable pharmacological properties, in particular an inhibiting effect on various receptor tyrosine kinases and on the proliferation of endothelial cells and various tumour cells, pharmaceutical compositions containing these compounds, their use and processes for preparing them.