Healthcare systems internationally need to consider new models of care to cater for the increasing numbers of people with asthma. Telehealthcare interventions are increasingly being seen by policymakers as a potential means of delivering asthma care. We defined telehealthcare as being healthcare delivered from a distance, facilitated electronically and involving the exchange of information through the personalised interaction between a healthcare professional using their skills and judgement and the patient providing information.To assess the effectiveness of telehealthcare interventions in people with asthma.We searched in the following databases: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, AMED, and PsycINFO; this was supplemented by handsearching of respiratory journals. We also searched registers of ongoing and unpublished trials.We selected completed randomised controlled trials of telehealthcare initiatives aiming to improve asthma care.Two review authors independently appraised studies for inclusion and extracted data and performed meta-analyses. We analysed dichotomous variables to produce an odds ratio (OR) and continuous variables to produce a mean difference.We included 21 trials in this review. The 21 included studies investigated a range of technologies aiming to support the provision of care from a distance. These included: telephone (n = 9); video-conferencing (n = 2); Internet (n = 2); other networked communications (n = 6); text Short Messaging Service (n = 1); or a combination of text and Internet (n = 1). Meta-analysis showed that these interventions did not result in clinically important improvements in asthma quality of life (minimum clinically important difference = 0.5): mean difference in Juniper's Asthma Quality of Life Questionnaire (AQLQ) 0.08 (95% CI 0.01 to 0.16). Telehealthcare for asthma resulted in a non-significant increase in the odds of emergency department visits over a 12-month period: OR 1.16 (95% CI 0.52 to 2.58). There was, however, a significant reduction in hospitalisations over a 12-month period: OR 0.21 (95% CI 0.07 to 0.61), the effect being most marked in people with more severe asthma managed predominantly in secondary care settings.Telehealthcare interventions are unlikely to result in clinically relevant improvements in health outcomes in those with relatively mild asthma, but they may have a role in those with more severe disease who are at high risk of hospital admission. Further trials evaluating the effectiveness and cost-effectiveness of a range of telehealthcare interventions are needed.