The objective of the present study was to develop a short prediction questionnaire for estimating the risk of no return to work (RTW) within 3 months of sick leave to facilitate triage and management of a patient population of subacute low-back pain (LBP) sufferers. We conducted a prospective study with a 3-month follow-up on 186 patients with LBP introducing a claim for sickness benefits to the largest sickness fund in Belgium. Patients completed a screening questionnaire within 2 weeks after claim submission. All patients were invited for clinical assessment, at 6-8 weeks of sick leave, by the medical adviser. Patients' work status was recorded by the sickness fund. About 20% of the patients did not resume work at 3 months' sick leave. They were more likely to experience pain below the knee, to have an own previous prediction of a 100% no RTW and to have a severe interference of pain on daily activities. The screening tool based on these three items correctly classified 73.7% of the non-resumers and 78.4% of the resumers at a cut-off score of 0.22. The findings of this study provide evidence of the utility of a short screening questionnaire for future use in intervention studies in a social security setting.