The objective of this study was to compare the effect of one-stage full-mouth disinfection (FMD) and conventional quadrant scaling in four weekly sessions (QS) on periodontal clinical parameters and halitosis among individuals with advanced chronic periodontitis. In this randomized controlled clinical trial, 30 individuals were divided into two groups: FMD (n=15) and QS (n=15). The following data were collected at the baseline and 90days after treatment: plaque index, tongue-coating index (TCI), bleeding on probing, probing depth, and clinical attachment level. Halimetry was performed by the organoleptic method, and the levels of volatile sulfur compounds (H2S and CH3SH) were measured by gas chromatography. The Chi-square, Fisher's exact, the Mann-Whitney, the McNemar, and the Wilcoxon tests were used for statistical analysis. Both groups showed statistically significant improvements in periodontal clinical parameters, reduction in TCI, organoleptic scores, and in CH3SH levels between times. However, major reduction was observed in FMD group. Non-surgical periodontal therapy, regardless of the protocol, was effective in improving periodontal clinical status of individuals, decreasing organoleptic scores and CH3SH levels between times, as well as reducing halitosis. This study contributed to the knowledge that non-surgical periodontal therapy, whether by FMD or QS, was effective in reducing halitosis in individuals with advanced chronic periodontitis.