Abstract: A cannula is retractably mounted with a needle holder (9) in a housing (5). A switching device (7, 8) allows the hollow needle (10) to be retracted after use into the housing (5). The needle holder (9) secures against rotation the hollow needle (10) in the housing (5) in a predetermined orientation. The housing (5) is preferably provided on its outer side with markings (13) which indicate the orientation of the hollow needle (10). The hollow needle (9) cannot twist when it is retracted. Another advantage is that the orientation of the needle point need not be determined before making an injection.