In every organisms, chromosomes are involved in two critical metabolic process, gene transcription and DNA replication, which seems to conflict with one another. In S phase the replication forks progress throughout the genome; inevitably compete for the DNA template with active RNA polymerases (RNAPs). The question how replication forks compete with transcription complexes during the process of replication is been noticeable in biology. Replication fork arrest due to the collision with transcription complex will lead to DNA damage response, mutagenesis and chromosomal deletions. This indicates that replication fork may occasionally collapse after collision with a RNA polymerase (RNAP). Several recent reports have highlighted the problems that occur when bacterial replication forks encounter transcription complexes, linking conflicts between genome duplication and gene expression to replication fork breakdown and Genetic instability. In this review we will look towards the reasons for collisions, and how cell counteracts these collisions?