Background Barrier methods for HIV and sexually transmissible infection (STI) prevention among women who have sex with women (WSW) are available, although their effectiveness has not been systematically investigated. These methods are infrequently used by WSW. As part of a larger study on STI risk perceptions and safer sex among African-American WSW, we discovered several misperceptions regarding barrier methods that may be associated with their limited use. Methods: Participants were recruited from the Jefferson County Health Department STI Clinic and through word of mouth in Birmingham, Alabama, for focus group discussions exploring perceptions of STI risk and safer sex. Results: Seven focus groups with 29 participants were conducted (age range: 19-43 years). Several misperceptions regarding barrier methods were identified, notably the conflation of dental dams and female condoms. Descriptions of the use of barrier methods were qualified with phrases suggesting their hypothetical, rather than actual, use. Additional evidence that barrier methods are not actually used came from beliefs that dental dams and female condoms are available in major grocery stores or department store chains. Conclusions: Those providing sexual health services to WSW should be cautious in assuming that WSW have accurate information regarding barrier methods for safer sex. Sexual health services provided to WSW should include an accurate description of what barrier methods are, how to distinguish them from barrier methods more commonly used during heterosexual sex (female and male condoms), and how to use them correctly. Future studies are needed to address how effectively these measures reduce transmission of STIs among WSW. © 2013 CSIRO.