Background: Complete reporting of seroepidemiologic studies is paramount to inform public health decision-making. The Reporting of Seroepidemiologic studies-SARS-CoV-2 (ROSES-S) guideline is a checklist that guides the reporting of SARS-CoV-2 seroepidemiological studies. Adherence of SARS-CoV-2 seroepidemiologic studies to the ROSES-S guideline has not yet been evaluated. Objectives: Evaluate SARS-CoV-2 seroepidemiologic study reporting by assessing adherence to the ROSES-S reporting guideline; determine whether publication of the ROSES-S guideline was associated with reporting completeness; and identify study characteristics associated with reporting completeness. Methods: A stratified random sample of SARS-CoV-2 seroepidemiologic studies was evaluated for adherence to the ROSES-S guideline. Study adherence to each reporting item was categorized as "reported", "not reported", or "not applicable". Percent adherence per reporting item and the median and interquartile range (IQR) adherence were reported across all items and by item domain. Beta regression analyses examined if study characteristics were associated with changes in the overall adherence scores. Results: 199 studies were analyzed. Median adherence to reporting items was 48.1% (IQR 40.0%-55.2%) per study, with no significant changes before and after guideline publication. Article publication source (p<0.001), study risk of bias (p=0.001), and sampling method (p=0.004) were associated with adherence to the ROSES-S guideline. Conclusions: There was suboptimal reporting in SARS-CoV-2 seroepidemiologic studies, which was associated with key study characteristics. Publication of the ROSES-S guideline was not associated with changes in reporting practices. Given the importance of complete reporting for the utility of seroprevalence data, authors should improve reporting.