A survey of nearly 2,500 overdose deaths in Pennsylvania last year shows nearly half involved heroin.
The U.S. Drug Enforcement Administration said the state ranks ninth in drug deaths per capita.
The report tallies 2,497 deaths, including 1,080 in Philadelphia and its four surrounding counties.
Allegheny County had 307 drug deaths.
DEA spokesman Patrick Trainor said the heroin sold in Philadelphia is unusually potent because the strong demand drives up quality.
Many of the deaths involve heroin mixed with painkillers or anti-anxiety drugs.
The report said that 80 percent of the victims were white and two-thirds were male. More than two-thirds were over 30.
The DEA does not have comparative figures for earlier years. But Trainor said that overdose deaths in Philadelphia are on pace to rise this year.