Paramedics called officers to the address in Harold Grove, Hyde Park, shortly before 3.30am today.
Also in crime: Solicitors, teacher and company directors among those arrested over child pornThey reported that a 32-year-old man had been found seriously injured there.
A West Yorkshire Police spokesman said: "Paramedics gave emergency treatment but the man was pronounced dead at the scene a short time later.
"The death is currently being treated as unexplained and a post mortem examination is due to take place later today to establish the cause of death."
Also in crime: Worst hotspots for vehicle crime in LeedsA 39-year-old man has been arrested in connection with the incident and is currently in custody.