OBJECTIVES: No guidelines exist in the approach that Evidence Review Groups (ERGs) should take to appraise search methodologies in the manufacturer’s submission (MS) in single technology appraisals (STA). As a result, ERGs are left to appraise searches using their own approach. This study investigates the limitations of manufacturers' search methodologies as critiqued by ERGs in published STA reports. METHODS: Limitations from search critiques in 83 ERG reports published in the NIHR website between 2006 and May 2011 were extracted. The limitations were grouped into themes. Comparisons were made between limitations reported in the clinical effectiveness versus cost-effectiveness searches. RESULTS: Over 60 different limitations were identified and sorted in seven broad themes: missing studies, search strategy, reporting, sources, limits, filters and translation. The search strategy theme contained the most limitations. Missing studies were frequently found by the ERG group in the clinical effectiveness searches. The omission of searches by manufacturers for unpublished and ongoing trials was frequently reported by the ERG. By contrast, failure of the manufacturer to report strategies was the most common limitation in the cost-effectiveness searches which may explain the number of missing critiques in some ERG reports. Themes with the most frequent limitations in both types of searches are search strategy, reporting and source. CONCLUSIONS: Variations exist in the limitations reported in both clinical and cost-effectiveness evidence searches in STAs. It is recommended that separate checklists or one that incorporates both reporting and search strategy appraisal be used to ensure that ERG groups and manufacturers are aware of the range of limitations that might exist when appraising searches.