Abstract Human acclimatization to passive stresses serves as the basis for understanding physiological responses to altitude exposure. Published research pertaining to swimming and endurance training is reviewed. It is argued that altitude training does not facilitate improved performances at sea-level because of the specificity of the acclimatization response. It is argued that if complete altitude acclimatization was to occur, it would not be possible to train with sufficient volume or intensity to maintain high levels of performance. Although the field contains many studies, those which are definitive lead to the conclusion that altitude training is not an avenue for enhancing the sea-level performances of highly-trained swimmers. The practice of conducting altitude training camps for elite swimmers is not justified on either physiological grounds or performance benefits. Conclusions Several applied principles are supported by good research. The generalizations offered here relate to moderate altitudes (2,000 - 3,000 m). 1.The athlete or team that is highly successful in competition at sea-level should be equally successful at altitude after acclimatization (Grover, Reeves, Grover, & Leathers, 1967). 2.Performance degradations are most pronounced in events which rely upon the aerobic energy system. Even at moderate altitude, performances will be impaired and, in some persons, will not improve with acclimatization (Faulkner, Daniels, & Balke, 1967; Sucec, 1996). 3.Upon return to sea-level, fully trained/elite athletes' performances are not improved as a result of training at altitude. Performances in one and two-mile events have been shown to be slower the third and fifteenth days after return (Buskirk, Kollias, Akers, Prokop, & Picon-Reategui, 1967). 4.VO2max and 2-mile performances are significantly decreased at days 1 and 3 at altitude in trained athletes. Only a slight (2%) improvement in altitude VO2max and 2-mile performance occurs after 18-20 days of acclimatization. Performances equal but do not exceed pre-altitude values on returning to sea-level. There is no potentiating effect of hard endurance training at altitude at 2,300 m over equivalent sea-level training on sea-level VO2max or 2-mile time in already well-conditioned middle-distance runners (Adams, Bernauer, Dill, & Bomar, 1975). 5.The maximum aerobic power and performance of highly trained athletes do not always improve with altitude acclimatization (Kolias & Buskirk, 1974). The training intensity required for maintaining peak performances cannot be achieved at altitude. Usually, training volume has to be reduced or rest intervals increased to accomplish "reasonable" training. 6.Training at altitude might enhance sea-level performance in originally less than maximally conditioned individuals (Fox et al, 1993, p. 469).