The ICH E14/S7B 2022 Q&As stipulate that in vitro hERG assessments should be conducted in accordance with Good Laboratory Practice (GLP). We present a GLP compliant study using the conventional manual patch-clamp technique in accordance with the ICH E14/S7B Q&A best practice guidelines to establish in-house IC50 values for ondansetron, moxifloxacin and dofetilide.