With the aim of describing the structure and process by which prenatal care is provided at the primary health care level in the city of Pelotas in southern Brazil, a descriptive cross-sectional study was conduced. All 31 urban health care facilities were visited and their structure analyzed. A total of 839 prenatal records from mothers who delivered in the six months prior to the beginning of the study were reviewed. The structure as a whole was classified as poor (only 70% of standard parameters were present), mainly due to deficiencies in the physical plant. Process assessment showed low coverage (53%) and an average of 5.3 visits. Only 37% of patient records showed adequate results (Kessner Index). Adding laboratory test results and routine procedures as complementary criteria, 31% and 5% of the records scored as adequate, respectively. In summary, overall quality of prenatal care provided at the primary health care level in Pelotas is poor. Mechanisms to increase staff adherence to both procedures and program logistics need to be developed.