Recognition of DNA by ligands and the interactions with the minor groove of DNA is a topic of growing interest in the fields of Chemistry, Biology and Medicine. Some of these compounds are sequence-selective DNA-interactive agents that bind covalently to guanine bases within the minor groove of DNA, modulating the activity of transcription factors or genes. In this regard, pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are of particular interest, as they recognize specific sequences of DNA and they have both antibacterial properties and selective cytotoxicity towards tumour cells. Naturally occurring PBDs (e.g. anthramycin) were originally isolated from a fermentation broth of various species of Streptomyces, although recently discovered limazepines A-F come from Micrococcus species. The second generation of PBDs, which is formed by dimers, has enhanced sequence selectivity and form both interstrand and intrastrand cross-links that are more difficult for tumour cells to repair, resulting in an increased cytotoxicity. As PBDs have attracted many chemists over the last few years, a wide range of analogues have been synthesized. It becomes necessary to outline the PBD dimer named SJG-136, which is the lead candidate currently undergoing pharmacology and toxicology studies due to its in vitro and in vivo activity against cancer cells.