Since 1990, Russia has experienced a dramatic increase in the number of abandoned children, associated with harsh socio-economic conditions, increases in drug and alcohol addiction and HIV infection. Approximately 20% of infants born to HIV-positive mothers are abandoned in Russia. To find out why, we conducted 266 qualitative interviews in 2004-05 in four Russian cities, including HIV-positive women who had abandoned their infants and others who had not, relatives of the women (mostly their mothers), HIV-negative women who had abandoned, and medical experts. Unintended pregnancy was cited as the most important factor influencing the decision to abandon. Other important determinants included lack of partner and family support, drug abuse, fear of birth defects or disabilities, negative attitudes of medical professionals, and marginalized socio-economic status. HIV infection was closely linked to many of these reasons. Important avenues for interventions among HIV-positive women emerged, including improved contraceptive information and provision, education of medical personnel and women on HIV prevention and treatment, enhancement of social support, and strengthening of fostering and adoption programmes for HIV-affected families.