Although the mother-to-child transmission (MTCT) contributes only 5% of transmission of HIV infection, its impact has reversed the decline in infant and child mortality rates. With antenatal service coverage of over 90%, the integration of prevention of MTCT (PMTCT) of HIV infection into the Reproductive and Child Health (RCH) services in Tanzania, this is likely to overstretch the staff capacity and undermine the already compromised quality of health care services. A retrospective study was conducted to assess the impact of integrating and scaling-up PMTCT of HIV infection into routine RCH services, on the magnitude of staff workload in RCH clinics. The study was conducted in 60 health facilities identified from five regions that had participated in the pilot phase of PMTCT implementation in the Mainland Tanzania. The average staff workload was calculated from staff-load obtained from attendance records and activity-time obtained by direct observation; and staff-time from records that were kept at the clinic. The average staff workload was found to be 50.5% (8–147%) for facilities providing PMTCT of HIV infection and 37.8% (11–82%) for facilities without PMTCT services. The average staff workload was computed on the assumption that all clients attending various antenatal clinics received PMTCT services from trained staff only and the result revealed staff workload of 87.2%. This study concludes that services for PMTCT of HIV infection can easily be scaled-up and integrated into RCH services using the already existing staff. In the wake of the human resource crisis in the health sector in developing countries, strategies to address the problem will need to go beyond numbers to address issues of staff productivity and their distribution.