The son of ousted president Mohamed Morsi, Abdallah Morsi, has been given one year in prison with labour and a fine of LE10,000 for possession of hashish.
His friend, Emad El-Shamy, received the same sentence.
The charges stem from an incident in March, when Abdallah and El-Shamy were stopped at a police checkpoint while on their way from the Nile Delta's Sharqiya governorate to New Cairo and were found with two hashish joints.
Both Morsi and El-Shamy were arrested and then released a day later upon agreeing to give blood and urine samples for a drug test.
At the time of their arrest, Morsi's brother, Osama, posted a statement on Facebook calling the allegations false and an attempt to "taint the image of honest people".
Wednesday's sentence – from Banha's Criminal Court, in Qalioubiya governorate – is the latest in a long line of trials and convictions handed out to allies of the Islamist president and his Muslim Brotherhood group since his ouster a year ago.
Morsi himself is currently facing several trials on a variety of charges, some of which could carry the death penalty.