BACKGROUND: Traditionally, clinical learning for medical students consists of short-term and opportunistic encounters with primarily acute-care patients, supervised by an array of clinician preceptors. In response to educational concerns, some medical schools have developed longitudinal placements rather than short-term rotations. Many of these longitudinal placements are also integrated across the core clinical disciplines, are commonly termed longitudinal integrated clerkships (LICs) and often situated in rural locations. This review aimed to explore, analyse and synthesise evidence relating to the effectiveness of longitudinal placements, for medical students in particular to determine which aspects are most critical to successful outcomes. METHOD: Extensive search of the literature resulted in 1679 papers and abstracts being considered, with 53 papers ultimately being included for review. The review group coded these 53 papers according to standard BEME review guidelines. Specific information extracted included: data relating to effectiveness, the location of the study, number of students involved, format, length and description of placement, the learning outcomes, research design, the impact level for evaluation and the main evaluation methods and findings. We applied a realist approach to consider what works well for whom and under what circumstances. FINDINGS: The early LICs were all community-based immersion programs, situated in general practice and predominantly in rural settings. More recent LIC innovations were situated in tertiary-level specialist ambulatory care in urban settings. Not all placements were integrated across medical disciplines but were longitudinal in relation to location, patient base and/or supervision. Twenty-four papers focussed on one of four programs from different viewpoints. Most evaluations were student opinion (survey, interview, focus group) and/or student assessment results. Placements varied from one half day per week for six months through to full time immersion for more than 12 months. The predominant mechanism relating to factors influencing effectiveness was continuity of one or more of: patient care, supervision and mentorship, peer group and location. The success of LICs and participation satisfaction depended on the preparation of both students and clinical supervisors, and the level of support each received from their academic institutions. CONCLUSION: Longitudinal placements, including longitudinal integrated placements, are gaining in popularity as an alternative to traditional block rotations. Although relatively few established LICs currently exist, medical schools may look for ways to incorporate some of the principles of LICs more generally in their clinical education programmes. Further research is required to ascertain the optimum length of time for placements depending on the defined learning outcomes and timing within the programme, which students are most likely to benefit and the effects of context such as location and type of integration.