It is widely accepted in forensic speech science that formants have speaker discriminatory power, and therefore formant measurements commonly feature in forensic speech casework. Courts in Northern Ireland even go as far as to insist that formant analysis has to be carried out as part of forensic voice comparison analysis. However, work in the broader phonetics field has started to challenge the weight that has been traditionally attached to formants in a range of related subdisciplines – this justifies a review of the use and performance of formants in forensic speech science research studies. This paper therefore presents part of a meta-analysis of forensic speech science studies which test formants as a parameter for speaker discrimination. The results are highly variable across the 277 results from the 37 papers included. Some performance trends that might be expected are not evident from this meta-analysis.