This paper investigated the effects of receptive and/or productive tasks on vocabulary gains. To achieve this end, a quick Oxford Placement Test (OPT) was administered to the senior students population studying English teaching at Khorasgan Azad university ,and based on their OPT scores, four advanced classes were randomly grouped as receptive, productive, mixed task and control groups. Fifteen target words were explicitly taught and practiced with receptive, productive, or mixed tasks . The groups were tested on receptive and productive tests before, immediately after, and 4 weeks after the applications of words. The results within groups revealed that all groups showed a statistically significant increase in their scores both in receptive and productive parts from pre tests to post tests. With regard to receptive tests, no significant decrease was observed in task groups from immediate to delayed post test. In the productive tests, on the other hand, although receptive task group was able to retain its gains from immediate to delayed post test, there was a significant decrease in the other groups over time. The present study also examined the receptive and productive vocabulary gains between groups to find out whether there was a significant difference in students’ receptive and productive vocabulary gains among the groups. Both in the receptive and productive tests, all groups receiving tasks (receptive, productive or mixed) significantly outperformed the control group. However, on no account were there significant differences between the groups which received different tasks, which may show that none of the tasks (receptive, productive or mixed) was better than the other to increase receptive or productive vocabulary gains. The results of this study can benefit teachers and students to become aware of the merits and demerits of vocabulary learning tasks.