Background and Purpose: Concern for adverse cardiovascular events and limited guidance regarding how to conduct aerobic exercise (AEx) testing for individuals poststroke are key barriers to implementation by physical therapists in stroke rehabilitation. This study aimed to describe the nature and safety of submaximal AEx testing protocols for people with subacute stroke (PwSS) and the nature of comorbidity of PwSS who underwent submaximal AEx testing. Methods: We conducted a scoping review and searched MEDLINE, EMBASE, PsycINFO, CINAHL, and SPORTDiscus from inception to October 29, 2020. Studies involving submaximal AEx testing with PwSS, reporting on participant comorbidity and on adverse events during testing, were eligible. Two reviewers independently conducted title and abstract and full-text screening. One reviewer extracted data; a second reviewer verified data. Results: Thirteen studies involving 452 participants and 19 submaximal AEx testing protocols (10 field test, 7 incremental, and 2 constant load) were included. Hypertension (41%), diabetes (31%), and dyslipidemia (27%) were the most common comorbidities reported. No protocols resulted in a serious adverse event. The most