Background: Clinical trials have proven a survival benefit from applying local therapies for oligometastatic cancers of various origin. Summary: Today, the definition of oligometastatic disease is based on limited lesion numbers and organ systems involved. Treatment guidelines by the European Organisation for Research and Treatment of Cancer (EORTC), European Society for Medical Oncology (ESMO) and several other groups suggest a threshold of up to 5 tumours. Established biological markers indicating the aggressiveness of a given tumour (and therefore suggesting local treatment only or the addition of or complete switch to systemic therapies) are missing, except for disease-free survival, the only recommended parameter for patient selection beyond lesion count. Key Message: The following article discusses clinical implications as well as local techniques established for the treatment of oligometastatic disease.