To investigate the effect of raising awareness of partial synformy on second language vocabulary perception and production, four groups of university students in a general English course were selected. Two of the four groups acted as experimental groups and the other two as control groups. The participants of the experimental groups were made aware of the orthographic similarities and contrasts whereas the control group participants were not. At the end of the experimental period, two of the four groups (one experimental and one control group) were given a multiple-choice test to compare their perception of words. To study the effect of partial synformy on vocabulary production, the other two groups were given a production task. An ANOVA procedure was applied, the result of which indicated meaningful differences between means. The follow-up Scheffe test showed that awareness of partial synformy positively influences both vocabulary perception and production.