The non-fluent/agrammatic variant of primary progressive aphasia is a neurodegenerative disorder characterized by effortful language production and impaired comprehension of grammatically complex sentences. Recently, interest in non-pharmacological interventions has increased, particularly regarding techniques that allow for non-invasive brain stimulation, such as transcranial direct current stimulation. The main purpose of this study was to investigate whether the use of anodal transcranial direct current stimulation applied to the dorsolateral prefrontal cortex during individualized language training for 25 min a day at 5 days a week for 2 weeks would lead to significant oral naming improvements in patients with agrammatic variant of primary progressive aphasia. Specifically, we hypothesized that anodal transcranial direct current stimulation plus individualized language training may improve the oral naming of treated and untreated objects compared with both placebo transcranial direct current stimulation plus individualized language therapy and anodal transcranial direct current stimulation combined with computerized cognitive training. Forty-seven agrammatic variant of primary progressive aphasia patients were consecutively enrolled and randomized into one of three groups that received the following treatments: (i) anodal transcranial direct current stimulation over the left dorsolateral prefrontal cortex during individualized language rehabilitation treatment; (ii) placebo transcranial direct current stimulation during individualized language rehabilitation treatment; or (iii) anodal transcranial direct current stimulation with computerized cognitive training. Clinical, neuropsychological and language assessments were recorded at baseline (T0), post-treatment (T1, 2 weeks) and at 12 weeks from T0 (T2). Magnetic resonance imaging data, functional magnetic resonance imaging data and blood samples were collected at T0 and T1. All of the groups demonstrated improvements in oral object naming at T1, with maintenance effects being observed at T2. At T1, the enhancement in the oral naming of treated and untreated objects was significantly greater in patients who underwent anodal transcranial direct current stimulation during individualized language rehabilitation treatment. There were no significant changes observed across the groups regarding the magnetic resonance imaging, functional magnetic resonance imaging or blood biochemical marker data. Our results support the beneficial effects of individualized language rehabilitation treatment in combination with anodal transcranial direct current stimulation in agrammatic variant of primary progressive aphasia patients.