Stuttering patterns may differ when comparing two languages. In bilinguals, specific patterns of stuttering in each one of the languages may potentially be found. This study reports on the case of a 27-year-old Spanish/English simultaneous bilingual whose dominant language is English. Speech and language testing was performed in both languages (language repetition, language understanding, vocabulary, reading, verbal fluency, spontaneous speech and conversational speech). Some differences in the stuttering distribution were found: stuttering in adjectives, adverbs and conjunctions occurred at least twice as much in Spanish as in English; stuttering was also more frequent in verbs in Spanish. Some hypotheses are presented to explain the differences in stuttering severity in both languages. It seems that when comparing stuttering in two different languages in the same subject, it is possible to find similarities in the stuttering pattern, suggesting general stuttering laws; but also differences, associated not only with language-specific idiosyncrasies but also with the individual's bilingualism characteristics. (Contains 7 tables and 2 figures.)