The attack happened Wednesday on the southbound E platform inside the 71st Avenue subway station around 10 p.m.
Authorities say the man got into an argument with the MTA employee and then punched the worker several times in the face before getting away on an E train.
The 51-year-old MTA employee was taken to the hospital and was said to be stable.
The union representing transit workers spoke out on Friday outside of Bronx Supreme Criminal Court where they demanded change and justice for one of their own.
The criminal trial is now underway for Isaiah Thompson who is accused of slashing a subway conductor in June of last year.
There have been at least seven reported attacks on transit workers on buses and in subway stations across the city since the start of the year.
Union leaders say while the NYPD beefed up patrols in the subways last year, the attacks persist and more needs to be done.
"We don't feel that the folks who attacked us and assaulted us are given adequate prison sentences, hopefully that stops today," said Chris Drummond with TWU Local 100.
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