The present study was undertaken to evaluate advanced breeding lines of chilli (Capsicum annuum L.) for their reaction to powdery mildew caused by Leveillula taurica under natural epiphytotic conditions during Kharif 2025–26. Forty-five advanced breeding lines along with four checks were evaluated based on mean per cent disease index (PDI), area under disease progress curve (AUDPC), disease grade and disease reaction. Considerable variation was observed among the genotypes for powdery mildew response. The mean PDI ranged from 3.7 per cent in Arka Harita to 65.0 per cent in ABL 4, while AUDPC ranged from 50.0 in Arka Harita to 917.8 in ABL 4. Among the advanced breeding lines, ABL 14 recorded the lowest mean PDI of 28.3 per cent and an AUDPC of 391.1, indicating comparatively lower disease development. Based on the 0–9 disease grading scale, Arka Harita exhibited a resistant (R) reaction, Arka Saphal showed a moderately resistant (MR) reaction, and ABL 14 was classified as moderately susceptible (MS). The remaining advanced breeding lines were categorized as highly susceptible (HS), including the checks BVC 42 and Byadgi Dabbi. No genotype exhibited immune or highly resistant reaction. The comparatively lower disease severity in ABL 14 indicates its potential as a useful source for further evaluation and breeding for improved powdery mildew response. The observed variation among the breeding lines provides scope for selection and utilization of promising material in chilli improvement programmes aimed at developing genotypes with enhanced tolerance to powdery mildew.