 Under what conditions should scientists trust experimental data that support some theoretical conclusion such as, for example, that DNA has a helical structure or that mitochondria are bounded by two layers of membrane? This is known as the problem of “data reliability”. Unreliable data are commonly referred to as “experimental artifacts” in biology, indicating their status as being “made” by the experimental procedure. This is somewhat misleading, as all data—whether they are reliable or artifacts—are made by the experimental procedure. The difference is that reliable data are correct representations of an underlying reality, whereas so-called artifacts are incorrect representations. This characterization assumes that data have some sort of representational content; they represent an object as instantiating some property or properties; (see Van Fraassen 2008, Ch. 6–7). The question of what it means for data to represent their object correctly has not been much discussed in this context. The focus so far has been mostly on various strategies for checking data for reliability, which will be discussed below. As for scientists themselves, they tend to place this problem under the rubric of replicability. While this is also an important topic, the fact that some data are replicable is not sufficient for their reliability. There are lots of well-known examples of perfectly replicable data that turned out to be not reliable, e.g., the case of the mesosome to be discussed below.