Objective: We aimed to assess the causal effects of fixed-guideway rapid transit systems (right-ofway bus, train, or railway) on health. Search methods: We searched Medline, Embase, CINAHL, TRID, GEOBASE, Web of Science, Academic Search Complete, Urban Studies Abstract, PsycINFO, Dissertations and Theses Abstracts and Index, and OpenGrey from January 2000 to November 2019. Selection criteria: We included longitudinal studies on pedestrians, workers, or the general population. We excluded infectious disease outcomes, occupational studies, and studies looking at the effect of implementation versus the service. Data collection and analysis: Two reviewers independently screened all titles, abstracts, and subsequently all full texts of potentially eligible articles for inclusion. In case of dissent, they discussed until reaching an agreement. After extracting data, one reviewer assessed the risk of bias and a second reviewer independently verified all data and assessments. Results were grouped by health outcomes. Main results: Our findings cover 11 quasi-experiments reporting health outcomes of 5412 participants, 204 households, 108 reporting districts, and two time-series analyses covering 16 years. Three as-if randomized studies and eight non-randomized studies were conducted in the United States (63.6%), other parts of North America (18.2%), South Africa (9.1%) and the United Kingdom (9.1%). Most evidence converged around physical activity or obesity, with an overall beneficial effect. Other positive outcomes included reducing vehicle collisions-injuries, homicides, and stroke. One study found a negative association between the intervention and subjective well-being. Authors' conclusion: Fixed-guideway transit seems to have an overall beneficial effect on health, likely related to increases in physical activity.