The work presented focuses on the need to better understand the effect environmental conditions, namely humidity, have on the interfacial shear strength (IFSS) of composites. The IFSS was first characterised using the microbond test method in a laboratory atmosphere. A specialised rig was then designed and manufactured in order to carry out the microbond test in a dynamic mechanical analyser with a humidity chamber accessory. Due to the well-known moisture absorbing nature of polyamide matrices, the effect of a range of conditions from 0 to 90% relative humidity was investigated. Results presented for both methods are based on the use of a Polyamide 6 matrix. Steel fibres are used extensively for method development and comparison throughout this work. Finally, successful testing on the primary system of fully sized HiPer-Tex (TM) glass fibre polyamide 6 effectively shows that humidity influences the measured apparent IFSS.