Short race distance swimmers should thoroughly regulate their breathing, because of the exchange of gases, on one side and wish for fewer breaths taken, because of the biomechanical advantages, on other. In addition, competitive swimmers use different practice means to overcome the need for breathing. Aim of our study was to find out the effects of apnea on 50 meters front crawl. Those efffects, observed in our study, were on swimming time, stroke and breathing frequency and subjective perception of exertion during swimming and fatigue after it. 18 competitive and ex-competitive swimmers swum 50 meters front crawl two times. Effects of apnea were observed in experimental swimming. In controled placebo swimming, 30 minute break was made between apnea and test swimming. The results showed that apnea did not affect on swimming time nor on stroke or breathing frequency on 50 meters front crawl. On the contrary, apnea affected on subjective perception of exertion during swimming and fatigue after it. The exertion feelings were lower and swimmers expressed less fatigue in experimental swimming, contrary to control placebo swimming.