The use of screening mammography among women 40 years of age and older in Los Angeles County was assessed through a random digit dial telephone interview. The sample of 802 women represents a large urban population with substantial proportions of blacks, Hispanics, and Asians. The survey obtained information regarding adherence to the ACS/NCI screening mammography guidelines, perceived benefits of early detection and mammography, perceived threat of developing breast cancer, and barriers to utilization. The results showed that 71% of the women had had at least one mammogram, with 49% having received a screening mammogram according to the guidelines for their age. Less than half the respondents knew the screening guidelines for their age, with women ages 40-49 years being less knowledgeable than women greater than or equal to 50 years old (29 vs 58% answering correctly). A logistic regression analysis predicting the likelihood of having obtained a screening mammogram according to the guidelines found the following to be predictive: concern over radiation (negative association), age (negative association), family history, knowledge of guidelines, and cost of a mammogram (negative association). Other demographic factors and beliefs were not significantly related to this dependent variable.