The lack of molecular modulators with well-defined activity and selectivity has been an added hurdle. Since the late 1970s, a few small molecules affecting the CPT enzymes, particularly inhibitors, have been identified. The oxirane carboxylic acids described by Tutwiler, Wolf, Sherratt, and Eistatter (BGLCF GmbH and McNeil) and the aminocarnitine derivatives described by Giannessi (Sigma Tau), Gandour, Anderson, and Griffith have been the most prominent and well characterized examples. These compounds have been used in an impressive number of in vitro and in vivo assays (including human clinical studies), assessing in particular potential effects in diabetes and cardiac failure. Nevertheless, or perhaps for this reason, a quantitative, consistent picture of relative and absolute activity, in vivo potency, selectivity, safety, and therapeutic potential of the various molecular entities is difficult to draft. In view of the complexity of the system, its sensitivity to a great number of factors, and the number of different setups that have been used to investigate its behavior, this is perhaps not surprising. It is important to stress at this stage that all compounds for which data are reported in the literature are nonselective inhibitors and affect more than one isoform of CPT (besides known or unknown off-target effects). Interest in this target, as documented by scientific literature, has been slowly but steadily growing in the past decades (Figure 2). A few reviews have been compiled that cover CPT inhibitors. This review will attempt to appraise the wide and tangled field of CPT modulators from the perspective of medicinal chemistry, using the chemotypes of CPT-interacting agents that have been described in the literature as a guiding beacon. Given the difficulty in obtaining quantitative comparable data for the activity and isoform specificity of these compounds, we believed that it would also be useful to include an evaluation of a few representative known pharmacological inhibitors of CPT in the same in vitro experimental setup (see Table 9).