Dyslexia can have determining effects on a person's learning identity, educational choices, and life in general. This is the first scientific report focusing on the remedial training prospects for adults with dyslexia. The main purpose of the research was to provide new information about reading disability in adults and to determine the usefulness of remedial training for dyslexia in Finland. In this research, the remedial effect of training material that was created to improve the reading performance of upper secondary education students was analyzed through two different remedial experiments. The results were analyzed through statistical analysis and students' own experiences. In addition, the functionality of the diagnostic method for dyslexia and reading disability in students were studied. The sample (n = 98) comprised students from two Finnish education institutes who participated in two remedial training experiments. The reading of the test group (n = 6) and the control group (n = 3) selected from the sample were studied for one study year. The test group was given 20 hours of remedial training for dyslexia while the control group was not. The research group (n = 37) in which the diagnostic method was tested comprised of students from two Finnish vocational schools. The research results showed positive development in students' reading during the remedial training period. Statistically significant decrease in the total number of reading errors and significant increase in reading speed were found. According to the results, the cerebral hemisphere-oriented tasks in the training material stimulated the weaker cerebral hemisphere, as expected. The training material for students with L-type dyslexia had a more positive effect than the one designed for students with P-type dyslexia.