Anabolic-androgenic steroids (AASs) are a subclassification of image performance enhancing drugs (IPEDs). While AAS use is most prevalent among people in athletics, there is also high lifetime prevalence of AAS use among prisoners. This study reports the qualitative detection of AASs in seized samples from the Scottish prisons from 2019-2023. Additionally, methods were developed for the quantitative analysis of AASs using gas chromatography-mass spectrometry (GC-MS) and applied to 61 samples of tablets or powders seized from Scottish prisons between July 2022 and July 2023. Since 2022, there has been an increase in AAS detections in the Scottish prisons. Oxymetholone was the most prevalent AAS, followed by metandienone (methandrostenolone, methandienone), methyltestosterone, oxandrolone, mestanolone (methylandrostanolone), stanozolol, and androstenedione. Multiple AASs were found in 21 samples and 10 samples contained other drugs, including amitriptyline, sertraline, zopiclone, mirtazapine, sildenafil, etizolam, Delta 9-tetrahydrocannabinol, and the synthetic cannabinoid MDMB-INACA. Most AAS samples were tablets (77.0%), although they were also detected in powders, herbal material, e-cigarettes, and a fragmented soap bar-type sample. There was a large variation in the concentration of AASs in the tablets and powders seized from the Scottish prisons, demonstrating AASs are another highly variable component of the polydrug use situation in prisons, the effects of which need to be examined further. This study reports the qualitative and quantitative detection of anabolic-androgenic steroids (AASs) in seized samples from prisons. Since 2022 there has been an increase in AAS detections with oxymetholone the most prevalent AAS, followed by metandienone, methyltestosterone, and oxandrolone. 34% of samples contained multiple AASs and 16% contained another drug. There was a large variation in the concentration of AASs in the tablets and powders, demonstrating AASs are another highly variable component of the polydrug use situation in prisons. image