Objectives Lay health workers (LHWs) are used in many settings to increase immunisation uptake among children. However, little is known about the effectiveness of these interventions. The objective of this review was to assess the effects of LHW interventions on childhood immunisation uptake. Methods We searched Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, British Nursing Index and Archive, AMED, POPLINE and WHOLIS, reference lists of included papers and relevant reviews, and contacted the authors of relevant papers. We selected randomised and non-randomised controlled trials, controlled before-after studies, and interrupted time series of any intervention delivered by LHWs and designed to increase childhood immunisation uptake. Two authors independently extracted data using a standard form and assessed risk of bias and evidence quality. Findings We identified twelve studies, ten of which were randomised controlled trials. Seven studies were conducted among economically disadvantaged populations in high-income countries. Five studies were from low- and middle-income countries. In ten studies, LHWs promoted childhood immunisation. In two studies, LHWs vaccinated children themselves. In most of the studies, the control group populations received no intervention or standard care. Most of the studies showed that LHWs increased immunisation coverage. However, study settings were diverse, allowing us to carry out only one meta-analysis including four studies. Conclusion LHWs could make an important contribution to achieving the Millennium Development Goal for child health. However, more high-quality studies are needed, particularly from LMICs. More studies are also needed to assess the effects of using LHWs to vaccinate children themselves. 2011 Blackwell Publishing Ltd.