OBJECTIVES: Frequency-domain analysis of heart rate variability (HRV) is an effective tool to evaluate autonomic balance. This study aimed to investigate gender differences in HRV among individuals undergoing regular resistance training. METHODS: This preliminary cross-sectional study was conducted from April to September 2016 in Joao Pessoa, Paraiba, Brazil. The low-frequency (LF), high-frequency (HF) and LF/HF ratio components of HRV spectral analysis were analysed among 22 men and 27 women undergoing regular resistance training. RESULTS: Among the male participants, the LF component was significantly increased compared to females in both the supine (1,171 +/- 192 versus 545 +/- 74 ms(2); P = 0.0067) and upright (1,824 +/- 260 versus 738 +/- 133; P = 0.0011) positions. The LF/HF ratio was also significantly increased in both positions among male participants (P <0.0500 each). CONCLUSION: These preliminary data suggest a possible gender difference in the HRV of individuals undergoing resistance training.