This article studies English as a foreign language (EFL) students’ production of English words that contain silent letters. The difficulties faced by Spanish native speakers when pronouncing words with silent letters in English have not been deeply studied. The study was conducted in a Costa Rican public university with 46 EFL students during one semester. Students were recorded while reading a set of given sentences that included silent letters. Then, three raters evaluated students’ pronunciation using a checklist. Data suggests that 1) around one-fourth of students have significant problems with the pronunciation of words with silent letters, 2) particular pronunciation rules prove more challenging for native Spanish speakers, 3) certain words negatively affect students’ performance. These results are consistent with the literature surveyed. Students’ scores suggest that the pronunciation of silent letters has not been adequately approached in pronunciation courses. These results should promote a curricular change where silent letter rules are progressively and systematically incorporated.This article studies English as a foreign language (EFL) students’ production of English words that contain silent letters. The difficulties faced by Spanish native speakers when pronouncing words with silent letters in English have not been deeply studied. The study was conducted in a Costa Rican public university with 46 EFL students during one semester. Students were recorded while reading a set of given sentences that included silent letters. Then, three raters evaluated students’ pronunciation using a checklist. Data suggests that  1) around one-fourth of students have significant problems with the pronunciation of words with silent letters, 2) particular pronunciation rules prove more challenging for native Spanish speakers, 3) certain words negatively affect students’ performance. These results are consistent with the literature surveyed. Students’ scores suggest that the pronunciation of silent letters has not been adequately approached in pronunciation courses. These results should promote a curricular change where silent letter rules are  progressively and systematically incorporated.