This quasi-experimental, retrospective study used birth certificate and medical record data to evaluate the effectiveness of the Rural Oregon Minority Prenatal Program (ROMPP) in improving patterns of prenatal care utilization by rural-dwelling, low-income, Mexican-American women at risk of poor pregnancy outcomes. The ROMPP intervention provided nursing case management services and peer outreach to pregnant Mexican-American women in a rural Oregon community. The intervention group had more prenatal visits in months 2, 3, 4, 5, 6, and 7 than the comparison group (P < 0.05). The intervention group had a similar number of emergency room (ER) visits, but had more respiratory diagnoses and fewer urinary tract infections. ROMPP women had more inpatient admissions and longer lengths of stay. No differences were found in the initiation of prenatal care or the total number of prenatal care visits, nor in the timing of screening serum glucose tests. The intervention should be expanded to address the persistent attitudinal, financial, transportation and language barriers to adequate prenatal care. Nurses should increase their cultural competency and sharpen their clinical focus on advocacy, marketing, facilitation of relationships between community groups, and community organizing.