This study examined the effects of humorous movie clips on better learning of English language vocabulary. Humor is an important human behavior that plays a vital role in communication and social interactions. This subject has been rarely investigated in Iranian English classes. The researchers used quantitative method. Because all of variables were not controllable, therefore quasi-experimental method was employed to conduct the study. To this end, a proficiency test was administered to 60 Iranian EFL learners. Then 48 intermediate language learners who were homogeneous based on their rank scores were chosen and randomly divided into two equal groups (i.e. 24 as experimental and 24 as control groups). To assess their vocabulary knowledge at the beginning of the study, both groups participated in a researcher-made, 30-items and multiple choice vocabulary test adapted from PET test and scored out of 30. Experimental group watched the humorous movie clips but the participants in control group taught in a conventional way. After 10 sessions of treatment, both groups were tested on the similar items covered in the pre-test. The effect of humorous movie clips on the groups’ vocabulary achievement was evaluated through Paired Samples t-test analysis. Results have shown that the experimental group outperformed the control group since humorous movie clips had a positive effect on developing vocabulary learning among intermediate EFL learners (p<05) in the experimental group. EFL teachers can use humorous movie clips to raise the learners’ motivation.