The aim of this paper is to analyse the intralinguistic factors which influence the usage of prothetic v- in the Prague vernacular. The analysis is based on linguistic interviews (each approximately 1 hour long) with 18 native Prague vernacular speakers between 20 and 30 years old. The material comprises a total of 3359 instances of the variable. Based on a binomial mixed model, it is concluded that the usage of v- is best explained by these predictors: gender, token length (counted in phonemes), prefixation, word class, the position of the variable (at the beginning vs. inside the word) and borrowedness of the word. On the other hand, phonological variables did not show any effect. A comparison of these data with the data from a study by Pavel Jančák (1974) suggests that the usage of v- in the Prague vernacular is on the slow decline.