This is a single arm, open label, multi-center phase 2 study to assess the safety and anti-tumor activity of intratumoral pIL-12 electroporation in subjects with stage IB to IIIB mycosis fungoides. All subjects may receive up to six cycles of treatment consisting of two treatment days, Days 1 and 8, in a 28-day cycle. Patients will receive intratumoral injection of pIL-12 at a concentration of 0.5 mg/mL and a fixed volume of 0.25 mL per each 1.0 cm diameter of target region, followed immediately by electrical discharge around the tumor site resulting in electroporation of plasmid DNA into tumor cells. Up to a maximum of 8 fixed volume injections followed by electroporation may be administered on each day of treatment and the total number is dependent upon the size of each individual lesion, or affected areas in erythrodermic patients. Prior to the first cycle of treatment, the investigator will select at least one lesion, or affected area in erythrodermic patients, to be left untreated for the duration of the study to allow for clinical observation of an untreated site. Subjects will be followed for safety and clinical evaluation every 4 weeks. Quality of Life will be assessed using the Skindex29, Functional Assessment of Cancer Therapy - General (FACT-G) and Visual Analog Scale for Pruritus (VAS-P) instruments. Survival follow up will occur at 3-month intervals over 2 years following end of study.