We developed a clinical score to monitor tuberculosis patients in treatment and to assess clinical outcome. We used the WHO clinical manual to choose signs and symptoms, including cough, haemoptysis, dyspnoea, chest pain, night sweating, anaemia, tachycardia, lung-auscultation finding, fever, low body-mass index, low mid-upper arm circumference giving patients a TBscore from 0 to 13. We validated the score with data from a cohort of 698 TB patients, assessing sensitivity to change and ability to predict mortality. The TBscore declined for 96% of the surviving patients from initiation to end of treatment, and declined with a similar pattern in HIV-infected and HIV-uninfected patients, as well as in smear negative and smear positive patients. The risk of dying during treatment increased with higher TBscore at inclusion. For patients with a TBscore of >8 at inclusion, mortality during the 8 months treatment was 21% (45/218) versus 11% (55/480) for TBscore <8 (p<0.001). TBscore assessed at end of treatment also strongly predicted subsequent mortality. The TBscore is a simple and low-cost tool for clinical monitoring of tuberculosis patients in low-resource settings and may be used to predict mortality risk. Low TBscore or fall in TBscore at treatment completion may be used as a measure of improvement.