Interviews were completed with 90 females serving sentences in 2 prisons in August 1984, an 84-percent sample of the total female inmate population. Prior drug usage was reported by 79 percent of the women, with two-thirds claiming to have used heroin alone or in conjunction with other drugs. The heroin users tended to be younger than the nonheroin offenders. They were more likely to have been convicted of drug or property offenses and to have experienced at least one prior conviction. A discussion of treatment approaches proposes that inmates who are heroin users experience detoxification within a separate, supervised unit. Because it appears that users had more interpersonal problems, small accommodation units are recommended. Almost one-third of the heroin users had not been involved in any community drug treatment program. Those who had been in treatment generally had tried therapeutic communities, detoxification, or counseling for short periods. Prisons should provide a range of treatments including small therapeutic communities and methadone blockade. Postrelease help is also recommended. 8 tables and 18 references.