This review examined effects of structured exercise (aerobic walking, with or without complementary modes of exercise) on cardiorespiratory measures, mobility, functional status, healthcare utilization, and quality of life in older adults (≥60 years) hospitalized for acute medical illness. Inclusion required exercise protocol, at least one patient-level or utilization outcome, and at least one physical assessment point during hospitalization or within 1 month of intervention. MEDLINE, Embase, and CINAHL databases were searched for studies published from 2000 to March 2015. Qualitative synthesis of 12 articles, reporting on 11 randomized controlled trials (RCTs) and quasi-experimental trials described a heterogeneous set of exercise programs and reported mixed results across outcome categories. Methodological quality was independently assessed by two reviewers using the Cochrane Collaboration Risk of Bias tool. Larger, well-designed RCTs are needed, incorporating measurement of premorbid function, randomization with intention-to-treat analysis, examination of a targeted intervention with predefined intensity, and reported adherence and attrition.