The aim of this study was to examine the physiological and psychological responses to an on-sight lead in comparison to an on-sight top rope ascent in elite level rock climbers. Fifteen (14 male, 1 female) rock climbers took part in the study, and were included based on having a self reported on-sight ability of ≥ 25 (Ewbank). Climbers attended three separate testing sessions; a maximum oxygen uptake test (VO2max), baseline session, and an attempt at one randomly assigned climb (lead or top rope) at the limit of their ability on an indoor artificial climbing wall. Before climbing perception of anxiety (Revised Competitive State Anxiety Inventory-2), blood lactate and plasma cortisol concentration were measured. Climb time, heart rate, oxygen consumption (VO2), blood lactate, plasma cortisol concentration and task load (National Aeronautics and Space Administration Task Load Index) were measured in response to the climb. Results indicated there were no significant differences in levels of somatic or cognitive anxiety, coupled with non-significant differences in plasma cortisol concentrations measured at various intervals during the climbing trial. Despite a 32 second difference in climb time between lead and top rope ascents there were no significant differences in blood lactate concentration, total average heart rate and VO2 between climbs. When reviewing VO2 averaged at each clipping point, lead climb VO2 was significantly lower at clips 1, 3 and 5 (P < 0.05). Task load was reportedly similar, with no significant differences in physical and mental demand between climbs. Our results indicate that the physiological and psychological responses of elite level climbers do not differ for lead and top rope on-sight ascents.