BACKGROUND. To increase the proportion of women who receive the recommended follow-up for mammographic abnormalities, factors which inhibit follow-up must be identified. Patient and health care delivery related factors were evaluated, stratified by type of follow-up recommendation, to determine reasons for inadequate follow-up. METHODS. All Caucasian and African American women at the Henry Ford Medical Group, in southeastern Michigan, with an abnormal screening mammogram result between January 1, 1992 and July 31, 1992 were identified. All women with inadequate follow-up, and a random sample of women with adequate follow-up, were invited to participate in a telephone interview that assessed three major dimensions of the Health Belief Model (susceptibility, benefits, and barriers), general health and health behaviors, and related characteristics. The relationship between these factors and inadequate follow-up was evaluated separately for women with immediate and 6-month follow-up recommendations, using univariate and multivariate analyses. RESULTS. A total of 555 women were invited to participate in the study (219 with inadequate follow-up and 336 with adequate follow-up). Interviews were completed for 418 women (75.3%). Women who were not notified of their mammographic abnormality were excluded from this study, leaving 399 women available for analysis. Among the women who had the recommended immediate follow-up, those who reported difficulty in obtaining medical appointments were 4 times more likely to have inadequate follow-up (95% confidence interval [CI] 1.5, 11.3), after adjusting for other variables. Among the women with six-month follow-up recommended, those who received fewer mammograms in the past 5 years were more likely to have inadequate follow-up (odds ratio [OR] = 4.0; 95% CI 1.6, 10.4). In this group, sociodemographic characteristics were not associated with inadequate follow-up, although women with transportation problems were at a higher risk (crude OR = 5.2; 95% CI 1.6, 16.7; adjusted OR = 3.1; 95% CI 0.5, 18.3). Among women with 6-month follow-up recommended, those who perceived their health as poor or fair (crude OR = 2.4; 95% CI 1.2, 5.1; adjusted OR = 2.3; 95% CI 0.8, 6.8) and those who did not examine their own breasts frequently (crude OR = 2.3; 95% CI 1.0, 5.4; adjusted OR = 2.7; 95% CI 0.5, 18.3) were also more likely to have inadequate follow-up. CONCLUSIONS. Results from this study demonstrate that the relative importance of factors associated with inadequate follow-up of abnormal mammograms differs according to the type of follow-up recommended. For both types of recommendations, the factors identified are noteworthy because they are amenable to intervention. Efforts should be made to facilitate appointment scheduling for follow-up of abnormal mammograms, and information about previous mammography screening should be obtained to identify women who are at a high risk for inadequate follow-up.