<b><i>Introduction:</i></b> The present work was carried out to determine the effectiveness of neuromuscular stimulation triggered by mirror therapy (MT) in older patients with post-stroke hemiplegia by two different intervention protocols, either intensively or spaced. <b><i>Methods:</i></b> A preliminary trial conducted on Spanish rehabilitation centres was conducted. Forty older patients (&#x3e;70 years) with diagnosed post-stroke hemiplegia were randomly distributed to intensive intervention group (5 times/week for 6 weeks) or to spaced intervention group (3 times/week for 10 weeks), which underwent a similar number of MT sessions (<i>n</i> = 30). Muscle strength and activity were measured at baseline and at the end of treatment. Functional ability was also evaluated. <b><i>Results:</i></b> Although both interventions improved muscle activity parameters, intensive MT showed a significantly and statistically higher intervention effect on electromyographic activity (<i>p</i> &#x3c; 0.001) and muscle strength (<i>p</i> &#x3c; 0.001) than the spaced over time protocol. Attending to the Barthel Index scores, the effect on functionality was also greater in the intensive therapy group (<i>p</i> &#x3c; 0.001), although the functional improvement measured by the Fugl-Meyer test was similar (<i>p</i> = 0.235). The effect of the interventions was independent of age and clinical antecedents. <b><i>Conclusion:</i></b> Intensive MT appears to be more effective than a more spaced over time therapy; therefore, at least in the older adults, this treatment protocol should be recommended in the post-stroke recovery of these patients. Further studies will confirm with certainty whether this treatment is the most suitable guideline for to treat these patients.