While provider-initiated HIV testing and counseling (PITC) programs are being increasingly implemented in antenatal care settings, there is scant information about the specific challenges providers face when offering these services. Through qualitative interviews with 30 HIV antenatal care providers from 10 clinics in central Uganda, we sought to understand specific challenges Ugandan providers face in implementing antenatal PITC programs, including how these challenges impact prevention of mother-to-child HIV transmission programs. Counseling-specific challenges included counseling discordant couples, incomplete follow-up of HIV-infected clients, low rates of both male involvement and HIV serostatus discourse, and inadequate training and support to carry out counseling duties. Health system challenges included lack of adequate space for counseling, frequent "stock-outs" of supplies, shortages of both counselors and lab personnel, and inadequate referral services. These challenges must be addressed in order to optimize the success of PITC programs at providing universal access to HIV testing and counseling services.