Objective To identify factors that influence the inter‐observer reproducibility of the routine, conventional Pap smear cytology (Pap smear test) in a network of certificated laboratories in a middle‐income Latin American country. Methods Twenty‐six laboratories provided each an average of 26 negative for malignancy ( NILM ) and high‐grade squamous intraepithelial lesion ( HSIL ) Pap smears. An external panel reviewed the slides. The kappa index and multilevel logistic regression were used to estimate the reproducibility and odds ratios ( OR ) of a false result with 95% confidence intervals (95% CI ), respectively. Results are presented for laboratories that collect (collector laboratories) and do not collect (non‐collector laboratories) samples. Results The agreements ranged widely (median kappa 0.51, range 0.16–0.70). The overall false‐positive ( FP ) and false‐negative ( FN ) rates were 31% (95% CI 27–35) and 11% (95% CI 7–17). Among collector laboratories ( N = 14), a bigger sample collection volume decreased the probability of a FP ( OR ‐adjusted 0.05, 95% CI 0.02–0.1) whereas the number of quality defects ( OR ‐adjusted 1.67, 95% CI 1.25–2.24), high workload ( OR ‐adjusted 5.52, 95% CI 3.85–7.92) and collection by cytotechnologists ( OR ‐adjusted 1.28, 95% CI 1.15–1.42) or health professionals ( OR ‐adjusted 2.26, 95% CI 2.04–2.49) instead of nursing assistants increased it. Among non‐collector laboratories ( N = 9), the FP rate increased with the number of quality defects ( OR ‐adjusted 1.86, 95% CI 1.06–3.26) but decreased if the samples were collected by health professionals instead of nursing assistants ( OR ‐adjusted 0.37, 95% CI 0.17–0.80). No significant associations were observed for FN . Conclusions Staff in charge of cervical sampling significantly determined the reproducibility of the Pap smear test, but this depended on whether the laboratory collects samples or read samples collected elsewhere.