This talk focuses on RNA export studied in vivo by single particle tracking and super resolution microscopy. (1) We analysed the export kinetics of single large ribosomal subunits (pre-60S particles) through single NPCs in human cells. Successful export has a single rate limiting step presumably corresponding to the release of the particle from the centre of the pore. Only about 1/3 of attempted export events are successful. Unsuccessful export terminates within the nuclear basket. (2) It is well known that the RNA helicase DDX19 (Dbp5 in yeast) plays a key role in establishing the directionality of mRNA export. We studied the DDX19 reaction cycle using a range of mutants in single particle tracking experiments of this protein and mRNA particles. From our data we yield a model of the DDX19 reaction cycle at the NPC.