Background: Noninferiority (NI) trials should help identify interventions that offer some benefit (eg, lower financial costs, more tolerable, or less invasive) without sacrificing noticeable effectiveness, and researchers should adhere to appropriate standards in the conduct and reporting of methods. This study describes the characteristics of a systematic sampling of NI studies from an updated search of recent published oncology trials. Methods: We performed a cross-sectional analysis of NI research published between 2014 and 2018 in the top 3 medical journals and top 3 oncology journals. We estimated the percentage of NI trials in oncology that report informative details of study, such as justification for conducting NI trial, justification of NI margin, analysis population, and alpha level. Results: There were 94 NI studies and 104 comparisons, and 59.6% (n=62) of comparisons declared NI. The median NI margin of comparisons reporting an odds or hazard ratio was 1.3 (1.05–3.2; n=64). Twenty-three percent (n=22) of studies did not provide a justification for conducting a NI study; 54.3% (n=51) of studies did not provide a justification of the margin they used in their study. Only approximately 46% (n=43) of comparisons used both an intention-to-treat (ITT) and per-protocol (PP) analysis, and 37.3% (n=35) of studies used a one-sided alpha level of >.025. There is notable variation in key elements of the conduct and reporting of NI trials, including the NI margin, the alpha level, and the population analyzed. Furthermore, a high number of studies do not provide justification for conducting a NI study or the margin used for determining NI. Conclusions: These results suggest that there is room for improvement in the reporting and conduct of NI trials in oncology.