Ametropia is quantified through refraction techniques. <em><strong>Objective:</strong></em> To determine the reliability of the Merchán monocular dynamic retinoscopy (MDR) in the measurement of refractive errors. <em><strong>Methods:</strong></em> In a descriptive study of concordance, 110 individuals (220 eyes) between the ages of eighteen and thirty were assessed with the MDR, static retinoscopy (SR), Jackson crossed cylinder (JCC) and the net of the MDR obtained by compensating the LAG of Nott’s retinoscopy (MDRc), with independent measurement by two evaluators in two different sessions. In the statistical analysis of refractions, the Fourier Transform notation was used. <em><strong>Results:</strong></em> The reproducibility found through the interclass correlation coefficient (ICC = 0.68) and the limits of agreement (± 1.02) was moderated with the MDR; concordance with SR (ICC = 0.63; LoA 95 % = ± 0.99) and the JCC (ICC = 0.44, LoA 95 % = ± 0.95) was moderated and poor, respectively. Between the MDRc with SR and the JCC the agreement was even poorer (SR, ICC = 0.275, LoA = ± 1.03; JCC, ICC = 0.190, LoA = ± 1.03). Conclusions: The MDR is a test with moderate reliability for quantifying ametropia in people and is not interchangeable with other refractive techniques.