Aphasia is one of the most complex speech and language disorders characterized by partial or total loss of the ability to communicate. It is mostly caused by the impairment of the central nervous system such as brain hemmorrhage or brain tumor. However, it can appear also after a person suffers a serious head trauma. There are three main types of aphasia- expressive aphasia, receptive aphasia and a mixed type of aphasia. This last type in a unique way combines the features and symptoms of the two previously mentioned types. Language abilities and speech defects of people suffering from aphasia have been investigated in this paper in order to confirm past researches. The results have shown the persons questioned differ greatly in recollection and implementation of grammatical rules, abundance of vocabulary and the ability of speech production in general. Furthermore, it has been shown that each of three types of aphasia affects the production and the understanding of speech in a specific manner. For example a person affected by a certain form of expressive aphasia will most likely experience difficulties such as limited vocabulary access and severe problems concerning the formation of sounds. On the other hand a person diagnosed receptive or mixed type of aphasia will most likely produce speech fluent in grammatical form but nonetheless far away from normal.