PURPOSE: Cardiac motion is a dominant source of physiological noise (PN) in myocardial arterial spin labeled (ASL) perfusion imaging. This study investigates the sensitivity to heart rate variation (HRV) of double-gated myocardial ASL compared with the more widely used single-gated method. METHODS: Double-gating and single-gating were performed on 10 healthy volunteers (n = 10, 3F/7M; age, 23-34 years) and eight heart transplant recipients (n = 8, 1F/7M; age, 26-76 years) at rest in the randomized order. Myocardial blood flow (MBF), PN, temporal signal-to-noise ratio (SNR), and HRV were measured. RESULTS: HRV ranged from 0.2 to 7.8 bpm. Double-gating PN did not depend on HRV, while single-gating PN increased with HRV. Over all subjects, double-gating provided a significant reduction in global PN (from 0.20 +/- 0.15 to 0.11 +/- 0.03 mL/g/min; P = 0.01) and per-segment PN (from 0.33 +/- 0.23 to 0.21 +/- 0.12 mL/g/min; P < 0.001), with significant increases in global temporal SNR (from 11 +/- 8 to 18 +/- 8; P = 0.02) and per-segment temporal SNR (from 7 +/- 4 to 11 +/- 12; P < 0.001) without significant difference in measured MBF. CONCLUSION: Single-gated myocardial ASL suffers from reduced temporal SNR, while double-gated myocardial ASL provides consistent temporal SNR independent of HRV. Magn Reson Med 77:1975-1980, 2017. (c) 2016 International Society for Magnetic Resonance in Medicine.