Ascents to altitudes above 3,050 m have been shown to cause adverse changes in symptoms and moods. The severity of these changes may depend not only on the altitude and rate of climb, but also on the length of stay and the effort expended to reach the desired altitude. In order to better understand how these factors influence symptom and mood changes during a climb, this study systematically assessed symptoms and moods during an ascent to 3,630 m. Self-rated symptoms and moods were determined in seven male volunteers over a period of 7 days (d) during a climb to 3,630 m of Mount Sanford, AK. The subjects were tested five times--twice at 2,225 m, then at 2,530, 3,080, and 3,630 m. Symptoms and moods were assessed with the Environmental Symptoms Questionnaire (ESQ) and the Profile of Mood States (POMS), respectively. Seven symptom factors and two mood factors were found to be adversely affected over time by the changes in altitude. More specifically, the subjects experienced more respiratory acute mountain sickness (AMS), exertion stress, and muscular discomfort and they were also colder, less alert, less vigorous, and more fatigued at higher elevations. These changes occurred primarily at 3,630 m and most also occurred at 3,080 m.(ABSTRACT TRUNCATED AT 250 WORDS)