To evaluate medium-term outcomes of overminus lens treatment in patients with intermittent exotropia [X(T)]. A retrospective analysis was performed of the outcomes of 19 children with X(T) who were prescribed overminus lens (-2.00 to -4.00 D) for a median period of 18 months (6-33). The success was evaluated using two assessment methods: 1. Newcastle Control System (NCS), and 2. Jampolsky's assessment. The mean age of the patients was 6.8 +/- 3.3 years (range 3-14 years). After the therapy, the median NCS score significantly improved from 5 to 1 (p < 0.001). Sixteen children (84 %) showed a NCS score of 2 or less after overminus lens treatment. According to Jampolsky's assessment, 84 % of the patients showed marked improvement from the baseline (47 % had qualitative improvement, 37 % quantitative decrease in the angle of deviation in addition to a qualitative improvement). The median pre-treatment distant angle decreased from 25 prism diopters (PD) to 18 PD after the treatment (p = 0.002). Overcorrecting minus lens treatment has a reasonable rate of success in the medium term and may be advised as primary therapeutic alternative for X(T). Both NCS and Jampolsky's scoring system appear to be useful and comparable for follow-up of patients with X(T).