This study was set up to examine factors affecting adherence to highly active antiretroviral therapy (HAART) by substance abusing women and to conduct a pilot study of a reminder device intervention. Three focus groups totaling 24 HIV-positive women developed priority lists of issues affecting adherence. Another group of 24 HIV-positive women received a timer-reminder with structured interviews on adherence at baseline and two monthly follow up intervals. Focus groups described key barriers to HAART adherence as substance abuse, forgetting, feeling ill, others' negative attitudes, obtaining refills and confidentiality. Primary disadvantages to HAART were side effects, pill-taking schedule and burden of taking medications. Facilitators included reminders (e.g. pill boxes) and spirituality. After receiving the reminder, missing a dose was less common (p<0.05) due to sleeping through dose, being busy and feeling too good while a favourable trend (p=0.07) was seen for change in daily routine and having too many pills to take. Although well accepted, the reminder did not affect the proportion missing a dose in the past two weeks: baseline (33%), first follow-up (30%) and second follow-up (30%). Forgetting to take HAART was only one of many cited barriers to adherence in these HIV-positive women; well-received reminder devices did not affect adherence. To improve substance-abusing women's adherence, multidimensional interventions are warranted.