A burden associated with electrophysiology is potential artifacts that look like physiological events, but are instead mistakenly incorporated into the experimental recordings. Two such artifacts discussed in this chapter are current run-up and current run-down. Simply put, baseline responses increase (run-up) or decrease (run-down) over time. Membrane channels recorded using cell-attached, whole-cell, and excised- patch configurations are all susceptible to run-up/run-down. The purpose of this chapter is to discuss empirically derived causes of run-up and run-down so that both errors can be either identified or avoided before or during current measurements. Unfortunately, data showing causes and solutions to run-up and run-down in all membrane channels does not exist. However, we discuss receptors and cell types that have been studied for the purpose of keeping the experimenter aware of problem solving strategies during electrophysiological measurements.