Abstract: The study investigates the influence of text messages on the proficiency in English Language of Undergraduates in Nigeria. The objective is to examine students use of short messages when texting: how often students use simple and correct English in text messaging; the kind of language or syntax used in text messaging; the errors identified in text messaging of Undergraduates especially in Adekunle Ajasin University, Akungba, Nigeria. The Survey Research Design Method was adopted. One hundred and fifty (150) students were used in the University. Three research questions were answered in the study. Descriptive Statistics was used to analyze the data collected. The findings revealed that students used short text messages when texting. They also design their text in slang during texting; It also revealed that University undergraduates do not use simple and correct English in text messaging; the most dominant kind of language used among them is whole word or phrase abbreviation. Also, students commit errors in test messaging, which include vowel deletion, graphones, alpha-numeric homophony, punctuation errors and initialization among others. In conclusion, text message or chatroom slang, affects students’ academic performance negatively. On the basis of the findings, it was recommended among others, that students should be more sensitized on the need to avoid SMS language in formal context of communication such as examination through special programmes conceived for such an objective. Such sensitization should not only be done for examination purposes, but for all others.