The aerodynamic drag associated with three types of commercially available running apparel (SS : nylon singlet and shorts ; L : nylon/spandex bodysuit and RS : nylon rainsuit) and two bodysuits of newly developed stretchable, water vapour permeable fabrics (T and K) was measured in a wind tunnel on a mannequin at four velocities (4.7, 7.1, 8.8 and 9.7m.sec-1). The effect of apparel on drafting efficiency was also examined by positioning a human subject on various grid coordinates around the mannequin and alternating the apparel worn by the subject and mannequin. Commercially available running apparel caused consistently higher drag than the T and K bodysuits. Under all conditions the high sheen and tight fit of the K fabric allowed drag reductions of between 17.5 and 7.4% at running speeds. A hood over the hair was responsible for 6 of the 7.4% reduction in drag noted with the K suit. It is estimated that reduction in drag of this degree provide real time savings of between 1.05% in the marathon to 2.75% in the 100m dash. A field trial of the K suit with 16 male subjects (mean age : 22 years) revealed a significant (p≤ .025) decrease in 100m running time amounting to a time saving of 1.17% at a velocity of 7.43m·sec-1. Results of the drafting investigations suggested that 1.0m is the optimal distance to draft behind a lead runner. At a forward velocity of 7.Im·sec-1 this practice provided a 62.7% reduction in drag. Further reductions in drag were possible if the following runner was clothed in the K apparel. Practical race strategies are suggested by these results and by the observation that running abreast a lead runner results in a larger shared drag than would be encountered by either runner alone.