Sen1 is a helicase that terminates transcription of non-coding RNAs but can also - independently -  remove RNA pol II from sites of conflicts with other DNA-associated processes. We are interested in the role of Sen1 at sites of conflicts of transcription with replication and with RNA pol I and RNA pol III transcription. Sen1 has also been involved in the resolution of R-loops, formed when the presumably nascent RNA associates with the DNA template strand. R-loops have physiological roles, but are also considered as genotoxic. I will present our work on the role of Sen1 in conflicts and will describe a new method, H-CRAC, to detect R-loops genomewide with unprecedented resolution and sensitivity. I will present unpublished data on the distribution of H-CRAC signals supporting a new model for the formation of R-loops in yeast.