Hoses used in hydraulics are known to fail. The total understanding of the failure mechanics doesn't seem to be known therefore a study is appropriate when a basis for a new product programme has to be set up.The approach in this task has been to look at different locations on a hose assembly where hoses fail and how it can be seen that the hose has failed. Some of reasons for the failures seem to be hypothesis rather than scientific evidence but it shows the authors best insight at the time of writing this text. The causes for failures has been grouped in two - the first being failures appearing at normal working conditions. The second being failures caused by abnormal conditions and wrong use. There has also been set up a list of phenomena, which seems to be responsible for the failures.