In the field of gynaecological oncology, which is characterised by the frequent application of cytotoxic drugs strongly necrotising to tissue, fully implantable venous port systems are of particular relevance. Frequent and serious complications such as infection, thrombosis, obstruction, leakage, or paravasation detract considerably, however, from the advantages otherwise deriving from a safe and reliable means of accessing a patient's venous system. Most complications are caused by the inexpert handling of these fully implantable catheters and should, therefore, be avoidable. In many cases, it will be possible after efficient diagnosis to solve the complication and keep the port functioning. On the basis of 8 actual cases typical and frequent complications observed in connection with port systems are described, together with preventive measures, diagnosis and therapy.