The aim of this paper was to analyze and compare the prevalence of HIV-related sexual risk taking among Croatian female sex workers (FSW) in two major urban areas. Two groups of FSWs were interviewed in Zagreb (n=65) and Split (n=89). Participants' mean age was 33.3 (SD=8.32). Interviews were conducted by outreach organizations that provide health services to sex workers in the two cities. The study used a brief questionnaire with standardized behavioral and HIV knowledge indicators. The two groups of FSWs differed significantly in most socio-demographic and socio-sexual indicators. Women from the Split sample were somewhat younger (chi(2)=6.87, p<0.05), less educated (chi(2)=7.71, p<0.05), less likely to be single (chi(2)=19.81, p<0.001), and less likely to be unemployed (chi(2)=5.22, p<0.05). In addition, they injected drugs in higher proportion (chi(2)=35.03, p<0.001), but had less clients in the preceding month (chi(2)=12.54, p<0.001) and were less likely to be abused by them (chi(2)=7.18, p<0.01). HIV testing was significantly more prevalent among participants in the Split sample (chi(2)=4.95, p<0.05). In multivariate analysis, selling sex in Zagreb (OR = 14.48, p<0.01), having secondary or higher education (OR = 4.76, p<0.05), ever tested for HIV (OR = 8.34, p<0.05), and having assessed the risk of getting infected with HIV as high (OR = 0.23, p<0.05) were significantly associated with consistent condom use with clients in the last month. The findings of this first systematic study on HIV-related risks among FSWs in Croatia point to the need to update targeted intervention programs by improving the prevention of HIV risks associated with injecting drug use (Split) and by a more efficient HIV educational approach.