Abstract Case-control studies are an important part of the epidemiologic literature, yet there remains a lot of confusion about how to interpret estimates from different case-control study designs. We demonstrate that not all case-control study designs estimate odds ratios. In contrast, case-control studies in the literature often report odds ratios as their main parameter even when using designs that do not estimate odds ratios. Therefore, only studies using specific case-control designs should report odds ratios, whereas the case-cohort and incidence density sampled case-control studies must report risk ratio and incidence rate ratios, respectively. This also applies to case-control studies conducted in open cohorts which often estimate incidence rate ratios. We also demonstrate the misinterpretation of case-control study estimates in a small sample of highly-cited case-control studies in general epidemiologic and medical journals. We therefore suggest greater care be taken when considering which parameter is to be reported from a case-control study.