Visual analogue scales (VAS) and verbal rating scales (VRS) are widely used to assess pain. Pupillary dilatation has been successfully used to measure pain in quantitative terms. Aims: The present study was conducted to study the correlation between VAS and pupillary diameter in the evaluation of postoperative pain. Materials and methods: This observational study was carried out on 60 patients 18–65 years of age, scheduled for lower abdominal surgical procedures under general anaesthesia. Postoperative pain assessment was done using the VAS at 6 h, 12 h, 18 h and 24 hrs. In addition, the pupillary diameter of both eyes was measured simultaneously. Results: Mean pupillary diameter values measured at baseline, 6 h, 12 h, 18 h, and 24 h postoperatively in two eyes, the difference was not statistically significant at any of the time points (P > 0.05), thus showing that the pattern of change in pupillary diameter was similar in both eyes. The mean change in pupillary diameter from baseline In both eyes was significant statistically at all the time points (P < 0.05). For VAS scores 0–2, 3–5, and 6–8, the mean change in pupillary diameter measured was 0.20 ± 0.3, 0.50 ± 0.53 and 0.42 ± 0.73 mm, respectively, thus showing a significant incremental trend (P < 0.001).