The pharmacological treatment of colorectal tumour leads to MultiDrug Resistance due to overexpression of several ABC transporters such as P-glycoprotein and some Multidrug associated Resistance Proteins (MRPs) that are able to efflux the chemotherapeutic agent out of the cell. A strategy to reverse MDR is the co-administration of antineoplastic agent with a P-glycoprotein inhibitor. These inhibitors are an useful tool for investigating, by PET, the expression and the activity of P-gp and MRPs that are overexpressed in chemoresistant colorectal tumor cells. In this review will be focused the aspect on P-gp and MRPs ligands employed as PET radiotracers considering their pharmacokinetic pharmacodynamic profile and their selectivity towards ABC transporters involved in chemoresistant cell of colorectal tumour.