Background : Mother -to- child transmission of HIV infection is the major source of infection under the age of 15 and global coverage of prevention of mother-to-child services reached 53% in 2009 .However, factors that influence utilization of PMTCT service and referral linkage to chronic ART clinic for HIV positive pregnant women are not well studied in Hawassa town. Objective: To assess factors that influence utilization of PMTCT service and referral linkage to chronic care before delivery in HIV positive pregnant women. Methods: Facility based cross sectional study was conducted in 6 Hawassa town public health facilities. Using systematic sampling procedure 588 study subject were included in the study. Indepth interview was also used to gather greater depth of information. A pretested structured questioner was used to collect data and the data analyzed using SPSS version 17. Moreover, bivariate and multivariate logistic regression model with crude and adjusted OR along with their 95% confidence interval were used to see the independent effect of factors influencing utilization of PMTCT service. Results: A total number of 588 pregnant women were included in this study. Five hundred thirty one (90.3%) of the respondents reported they had under gone voluntary counseling and testing and 522(98.67%) of those who were tested received the test result and Four hundred ninety nine (95.6%) were negative and twenty three (4.4%) were positive. Out of 23 women who were positive HIV status twenty women were linked to chronic ART care service 12 of them with formal referral linkage and eight of with non-formal and nine of those who were linked to chronic ART care service started HAART while seven started ARV prophylaxis. Pregnant women who were two or more number of ANC attendance were more likely to utilize PMTCT service when compared to other sources [AOR=2.99% CI=1.44, 6.23]. The pregnant women believed that their husbands support couple testing were associated with utilization of PMTCT service [AOR=16.2,95% CI= 6.58, 39.67].The pregnant women who support the idea of every pregnant should be tested also associated with utilization of PMTCT service [AOR=9.86, 95% CI=3.67, 26.51]. Conclusion: partner involvement, increasing access of women to VCT, community based education and sensitization targeted to the women and promoting PMTCT service to all facility and improving referral system and getting feedback between facilities will create good referral system between facilities is recommended. VII