Teaching technical vocabulary in ESP context is a vital part of English language teaching at a university level. EFL teachers almost use traditional techniques for teaching new medical vocabulary. This study aimed at examining the impact of teaching medical vocabulary through collocations on vocabulary learning of medical students. This quasi-experimental study with a pretest/posttest control group design was conducted on 80 students majoring Nursing at Kashan University of Medical Sciences, Iran. The proficiency test was used to determine the proficiency level of the students and 62 students were selected as intermediate students. The students were assigned into two groups. In the experimental group new medical vocabulary was taught through collocations, while in the control group new vocabularies were instructed through traditional techniques including synonym, antonym, definition and mother tongue translation. Data were collected using a researcher-made test of collocation. Results showed that the mean score of teaching medical vocabulary was increased in the experimental group after the treatment. It can be seen that the experimental group outperformed the control group on the medical collocation tests.