In recent years, the popularity of a new class of dietary supplements called multi-component pre-workout supplements (MIPS) has increased. These supplements are intended to be taken before training and usually contain a mixture of ingredients such as caffeine, creatine, beta-alanine, amino acids and nitric oxide agents, the combination of which can have a synergistic effect on the effectiveness of exercise and subsequent adaptation to training compared to individual ingredients. Therefore, the purpose of this article was to review the theoretical rationale and available scientific data assessing the potential ergogenic value of acute and chronic MIPS intake, to address potential safety issues associated with MIPS supplementation and to highlight potential areas for future research. Although direct comparisons between MIPS formulations or between MIPS and a single ingredient are difficult and often impossible due to the widespread use of "proprietary blends” that do not disclose specific amounts of ingredients in a given formulation, a significant body of evidence suggests that acute intake of MIPS before training can positively affect muscle endurance and subjective mood, although mixed results have been reported regarding the acute effects of MIPS on strength and power production.