MQM leaders alleged that several party members had been arrested by law enforcement agencies, while many were missing.
The missing workers' families also participated in the protest.
The party leaders Dr Farooq Sattar, Amir Khan, Kunwar Naveed Jameel, Mohammad Hussain, Zareen Majeed, and Amin-ul-Haq also joined the protest.
The protesters were carrying banners and pictures of the missing party activists. They shouted slogans and demanded their immediate release.