Objective. To provide a clinically relevant overview of the analytical interference by contrast agents (CA) in laboratory blood test measurements. Materials and Methods. The effects of five CAs, gadobutrol, gadoterate meglumine, gadoxetate disodium, iodixanol, and iomeprol, were studied on the 29 most frequently performed biochemical assays. One-day-old plasma, serum, and whole blood were spiked with doses of each agent such that the gadolinium agents and the iodine agents reached concentrations of 0.5mMand 12mg iodine/mL, respectively. Subsequently, 12 assays were reexamined using 1/2 and 1/4 of these CA concentrations. The results were assessed statistically by a paired Student’s t-test. Results. Iodixanol produced a negative interference on the bicarbonate (p = 0.011), lactate dehydrogenase (p < 0.0001), and zinc (p = 0.0034) assays and a positive interference on the albumin (p = 0.0062), calcium (p < 0.0001), ionized calcium (p = 0.0086), iron (p < 0.0001), and potassium (p = 0.0003) assays. Iomeprol produced a negative interference on the bicarbonate (p = 0.0057) and magnesium (p = 0.0001) assays and a positive interference on the calcium (p < 0.0001) and potassium (p = 0.0012) assays. Gadoxetate disodium produced a negative interference on the iron (p < 0.0001) and zinc (p < 0.0001) assays and a positive interference on the sodium (p = 0.032) assay. Conclusion. CAs cause analytical interference. Attention should be given to the above-mentioned analyte-CA combinations when assessing laboratory blood test results obtained after CA administration.