Mannarino, P, Matta, T, Lima, J, Simão, R, and Freitas de Salles, B. Single-Joint Exercise Results in Higher Hypertrophy of Elbow Flexors Than Multijoint Exercise. J Strength Cond Res XX(X): 000–000, 2019—Recent data suggest that single-joint exercises are unnecessary to maximize the resistance training (RT) results in novice to advanced individuals. However, the present literature is still inconsistent on this topic and controversy arises. The aim of this study was to compare the effects of the unilateral dumbbell row (DR) (multiple-joint) vs. unilateral biceps curl (BC) (single-joint) exercises on strength and elbow flexors muscle thickness (MT). Ten untrained men were assigned to an 8-week RT program for elbow flexors, one arm performing DR and the other performing BC in a within-subject design. After a familiarization, pretraining MT was measured using an ultrasound (US) technique, and strength was tested using 10 repetition maximum (10RM) tests. After pretesting, 8 weeks of RT (4–6 sets, 8–12 repetitions to concentric failure, 2 sessions per week) was performed. Post-testing was conducted in the same order as pretesting 48 and 72 hours after the last session. Single-joint BC exercise resulted in higher hypertrophy of elbow flexors (11.06%) than the DR (5.16%) multijoint exercise after 8 weeks of RT (p = 0.009). The 10RM improvement was higher for DR in DR-trained arm, whereas 10RM for BC was higher in BC-trained arm. The single-joint exercise resulted in higher hypertrophy of the elbow flexors than multijoint exercise after 8 weeks of RT, whereas strength improvements were greater in accordance with specificity of RT exercise. Therefore, in RT prescription for elbow flexors hypertrophy, single-joint exercises such as BC should be emphasized.