OBJECTIVES: To assess how long the UK's National Institute for Health and Clinical Excellence's (NICE) Technology Appraisal Programme has taken to produce guidance and to determine independent predictors of time to guidance. DESIGN: Retrospective time to event (survival) analysis. SETTING: Technology Appraisal guidance produced by NICE. DATASOURCE: All appraisals referred to NICE by February 2010 were included, except those referred prior to 2001 and a number that were suspended. OUTCOME MEASURE: Duration from the start of an appraisal (when the scope document was released) until publication of guidance. RESULTS: Single Technology Appraisals (STAs) were published significantly faster than Multiple Technology Appraisals (MTAs) with median durations of 48.0 (IQR; 44.3-75.4) and 74.0 (IQR; 60.9-114.0) weeks, respectively (p <0.0001). Median time to publication exceeded published process timelines, even after adjusting for appeals. Results from the modelling suggest that STAs published guidance significantly faster than MTAs after adjusting for other covariates (by 36.2 weeks (95% CI -46.05 to -26.42 weeks)) and that appeals against provisional guidance significantly increased the time to publication (by 42.83 weeks (95% CI 35.50 to 50.17 weeks)). There was no evidence that STAs of cancer-related technologies took longer to complete compared with STAs of other technologies after adjusting for potentially confounding variables and only weak evidence suggesting that the time to produce guidance is increasing each year (by 1.40 weeks (95% CI -0.35 to 2.94 weeks)). CONCLUSIONS: The results from this study suggest that the STA process has resulted in significantly faster guidance compared with the MTA process irrespective of the topic, but that these gains are lost if appeals are made against provisional guidance. While NICE processes continue to evolve over time, a trade-off might be that decisions take longer but at present there is no evidence of a significant increase in duration.