Background Sciatica has a substantial impact on patients and society. Current care is ‘stepped’, comprising an initial period of simple measures of advice and analgesia, for most patients, commonly followed by physiotherapy, and then by more intensive interventions if symptoms fail to resolve. No study has yet tested a model of stratified care in which patients are subgrouped and matched to different care pathways based on their prognosis and clinical characteristics. Objectives The objectives were to investigate the clinical effectiveness and cost-effectiveness of a stratified care model compared with usual, non-stratified care. Design This was a two-parallel group, multicentre, pragmatic, 1 : 1 randomised controlled trial. Setting Participants were recruited from primary care (42 general practices) in North Staffordshire, North Shropshire/Wales and Cheshire in the UK. Participants Eligible patients were aged ≥ 18 years, had suspected sciatica, had access to a mobile phone/landline, were not pregnant, were not receiving treatment for the same problem and had not had previous spinal surgery. Interventions In stratified care, a combination of prognostic and clinical criteria associated with referral to spinal specialist services was used to allocate patients to one of three groups for matched care pathways. Group 1 received advice and up to two sessions of physiotherapy, group 2 received up to six sessions of physiotherapy, and group 3 was fast-tracked to magnetic resonance imaging and spinal specialist opinion. Usual care was based on the stepped-care approach without the use of any stratification tools/algorithms. Patients were randomised using a remote web-based randomisation service. Main outcome measures The primary outcome was time to first resolution of sciatica symptoms (six point ordinal scale, collected via text messages). Secondary outcomes (at 4 and 12 months) included pain, function, psychological health, days lost from work, work productivity, satisfaction with care and health-care use. A cost–utility analysis was undertaken over 12 months. A qualitative study explored patients’ and clinicians’ views of the fast-track care pathway to a spinal specialist. Results A total of 476 patients were randomised (238 in each arm). For the primary outcome, the overall response rate was 89.3% (88.3% and 90.3% in the stratified and usual care arms, respectively). Relief from symptoms was slightly faster (2 weeks median difference) in the stratified care arm, but this difference was not statistically significant (hazard ratio 1.14, 95% confidence interval 0.89 to 1.46; p = 0.288). On average, participants in both arms reported good improvement from baseline, on most outcomes, over time. Following the assessment at the research clinic, most participants in the usual care arm were referred to physiotherapy. Conclusions The stratified care model tested in this trial was not more clinically effective than usual care, and was not likely to be a cost-effective option. The fast-track pathway was felt to be acceptable to both patients and clinicians; however, clinicians expressed reluctance to consider invasive procedures if symptoms were of short duration. Limitations Participants in the usual care arm, on average, reported good outcomes, making it challenging to demonstrate superiority of stratified care. The performance of the algorithm used to allocate patients to treatment pathways may have influenced results. Future work Other approaches to stratified care may provide superior outcomes for sciatica. Trial registration Current Controlled Trials ISRCTN75449581. Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 49. See the NIHR Journals Library website for further project information.