Xiao, F, Yang, Y, Xiao, L, Xia, Z, Wang, L, Yang, K, and Wang, S. Reduction of T cells and hsa-miR150-5p in female canoeing athletes: Preliminary evidence between exercise training and immune. J Strength Cond Res 36(11): e106–e113, 2022—This article aims to reveal the alteration of immune profile in teenage canoeing athletes, by which applies a clue for regulation of exercise on human immune. Thirty-one teenagers of female canoeing athletes and age-matched subjects participated in this research. Peripheral leukocytes' microRNAs (miRNAs) were analyzed using Agilent human microRNA 2.0 and gene software. The miRNA candidates were quantified by reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR). The percentages of various lymphocytes were tested using flow cytometry. There were 6 miRNAs (hsa-miR150-5p, 31-5p, 3659, 4419a, 650, and 8485) lower in canoeing athletes, and the reduction of miR-150 was identified by RT-qPCR (p = 0.021). Canoeing athletes had lower percent of CD3+ T cells than the subjects with no exercise training had (p < 0.001), but the ratio of CD4+ to CD8+ and the percent of CD4+ T cells and CD8+ T cells showed no significant difference between these 2 groups. T cells and hsa-miR150-5p are sensitive to the long-time heavy exercise training, and the exercise for winning competition regulates the immune system by inhibiting T cells and hsa-miR150-5p.