In toxocariasis, the enzyme-linked immunosorbent assay (ELISA) positive results require further antibody response characterization. The cross-sectional serological study aimed to assess the distribution of the avidity index (AI) of immunoglobulin G (IgG) against Toxocara canis in adults in Almaty and its association with the strength of the positive ELISA results. In April–May 2026 a total of 500 volunteers aged ≥18 were assessed. IgG were detected by the indirect ELISA with the native antigenic fraction 20–22 kDa upon 1 : 5 serum dilution. Avidity was determined upon 1 : 100 dilution and treatment with 6.0 М urea for 10 min at 20–25 °C. AI was calculated as the ratio of the optical density (OD) with the denaturing solution to the OD without it, multiplied by 100%. IgG were detected in 93 subjects out of 500 — 18.6% (95% confidence interval: 15.4–22.2%); all 93 positive samples were tested for avidity. The median AI was 79.2% (interquartile range: 52.7–90.7%). AIs < 40% were found in six samples (6.5%), 80–100% — in 34 (36.6%), >100% — in 12 (12.9%). Median IAs of the weakly positive, positive, and strongly positive groups were 85.4% (80.0–90.0%), 87.3% (66.7–95.8%), and 51.2% (44.9–62.3%), respectively; interquartile ranges are shown in parentheses. There were differences between distributions based on the Kruskal–Wallis test (p < 0.001). The stronger ELISA result was not associated with the successive AI increase. Avidity analysis complements the characteristics of IgG-positive samples, but does not determine the duration or activity of infection. The AI values >100% should be recorded separately and further verified through analysis.