Methotrexate (MTX) is an antimetabolite of folate that was originally developed as an antimalignancy drug. It was first introduced in the dermatology field by Gubner in 1951 after his incidental finding that psoriatic lesions improved after MTX treatment in a patient with cancer.1 Currently, MTX is used in a vast array of dermatological conditions. It has antiproliferative properties at a high dose and anti-inflammatory properties at a low dose through the inhibition of dihydrofolate reductase enzyme (DHFR). Reduced libido/impotence is considered a rare adverse effect (AE) of MTX. We report a case of a man with lymphomatoid papulosis (LP) who developed reduced libido after treatment with MTX. To our knowledge, only a few cases with loss of libido/impotence after MTX have been reported in the literatures. Dermatologists should be aware of this AE and discuss it with any patient for whom MTX is planned.