Senna, G, Willardson, JM, de Salles, BF, Scudese, E, Carneiro, F, Palma, A, and Simão, R. The effect of rest interval length on multi and single-joint exercise performance and perceived exertion. J Strength Cond Res 25(11): 3157–3162, 2011—The purpose of this study was to compare repetition performance and rating of perceived exertion (RPE) with 1-, 3-, or 5-minute rest intervals between sets of multi and single-joint resistance exercises. Fifteen resistance trained men (23.6 ± 2.64 years, 76.46 ± 7.53 kg, 177 ± 6.98 cm, bench press [BP] relative strength: 1.53 ± 0.25 kg·kg−1 body mass) completed 12 sessions (4 exercises × 3 rest intervals), with each session involving 5 sets with 10 repetition maximum loads for the free weight BP, machine leg press (LP), machine chest fly (MCF), and machine leg extension (LE) exercises with 1-, 3-, 5-minute rest intervals between sets. The results indicated significantly greater BP repetitions with 3 or 5 minutes vs. 1 minute between sets (p ≤ 0.05); no significant difference was evident between the 3- and 5-minute rest conditions. For the other exercises (i.e., LP, MCF, and LE), significant differences were evident between all rest conditions (1 < 3 < 5; p ≤ 0.05). For all exercises, consistent declines in repetition performance (relative to the first set) were observed for all rest conditions, starting with the second set for the 1-minute condition and the third set for the 3- and 5-minute conditions. Furthermore, significant increases in RPE were evident over successive sets for both the multi and single-joint exercises, with significantly greater values for the 1-minute condition. In conclusion, both multi and single-joint exercises exhibited similar repetition performance patterns and RPE, independent of the rest interval length between sets.