To clarify the principles of water vapour transfer through waterproof breathable garments during wear, we carried out three wear trials, i.e. resting, exercising and rainy procedures in a climate chamber. Three waterproof breathable and one impermeable garments were assessed in terms of their moisture accumulation in undergarments. It was found that both in steady conditions and in rainy conditions, the waterproof breathable garments are much more comfortable because of their good water permeability.