This diploma thesis analyses the distribution of intensifiers in adjective and adverb phrases in the British National Corpus. The theoretical part briefly introduces the two aforementioned types of phrases. The following sections provide a detailed overview of intensifiers, describing their history and development, factors that may influence their distribution as well as mentioning popular intensifiers in present-day English. The attention is then paid to the classification of intensifiers and to the description of individual categories. The practical part of the thesis examines and compares the occurrence of selected intensifiers in spoken and written British English, focusing on their frequency, semantic properties and collocational behaviour.