OBJECTIVES: The quality of evidence used in manufacturers’ submissions to health technology assessment (HTA) bodies is an important factor for the success of technology appraisals (TA). Indirect comparisons (IC) and network meta-analyses (NMA) are used in health policy decisions via the clinical effectiveness evidence in HTA submissions to the National Institute for Health and Care Excellence (NICE). The aim of this study was to: (i) assess the use of ICs and NMAs in HTA submissions to NICE; (ii) identify criticisms of ICs and NMAs in TAs generated by NICE and the Evidence Review Group (ERG); (iii) provide key insights and recommendations to minimise criticism of an IC or NMA in future HTA submissions. METHODS: The NICE website was interrogated to identify both TAs and the associated ERG/final appraisal document reports published from January 2013 to June 2015 in any therapeutic setting. RESULTS: A large proportion of the TAs analysed included ICs or NMAs. Common criticisms were related to the identification of data and the study selection for inclusion, study heterogeneity and the inadequate reporting of methods and analyses. CONCLUSIONS: The majority of criticisms of evidence synthesis submitted to NICE were related to issues around the primary evidence included in the analyses rather than the statistical methods of the analyses. To avoid many of the criticisms identified in this study a transparent approach to the reporting of the ICs and NMAs (and systematic review) is recommended.