The main subject of this essay is English loan words in Modern Swedish. The 39 loan words, which have been analyzed in the essay, were all borrowed during the 20th century, when a great number of loan words with English origin entered Swedish. The loan words were selected from 'Underdog', which was written by Torbjörn Flygt in 2001. The borrowing of English words is facilitated by the fact that the two languages are closely related. The study shows that the loan words belong to various different word classes, such as nouns, verbs, adjectives and adverbs, but that it is the nouns that are in majority. There are both concrete and abstract nouns among the loan words, but the concrete nouns are in majority. All of the nouns were count nouns in Swedish. The nouns take different plural endings in Swedish. The analysed verbs were both transitive and intransitive. All verbs were regular in both in Swedish and in English. Most of the adjectives and adverbs consisted of one-root morphemes. Many of the loan words have a touch of slang language in Swedish, even if that is not the case in English. The loanwords are divided into three major categories with different sub categories. The major categories are the direct loans, the loan translations and the constructed loans. The direct loans are easiest to recognise, whereas the loan translations and above all the constructed loans are hardest to identify as loans. The study also shows that languages affect each other when they meet. The major language is more likely to affect the minor language than the other way around. The giving language can influence the borrowing language at all levels of the language. Loan words can create problems when they are to be inserted into Swedish. The problems can be related to the choice of the ending in the plural, the spelling and the pronunciation.