The effect performed by traditional fermentation on the sensory coffee quality in Caturra and Castillo varieties was determined. These varieties grown in seven (7) municipalities of Narino, which were classified into two agroclimatic cluster (cluster A≤1650 m.a.s.l. and cluster B=1651-2100 m.a.s.l.). Temperature, pH, concentration of lactic acid and glucose were monitored every three hours. The samples were evaluated in final sensory quality. The average fermentation time was 18,75±3,2 and 18,94±3,4 hours for Caturra and Castillo, respectively. The pH decreased during fermentation from 5,5±0,35 and 5,6±0,26 to 4,4±0,34 and 4,4±0,5 for Caturra and Castillo, respectively. The environmental temperature was located in a range from 19,1 to 21,1oC (cluster A) and from 17,9 to 20,1°C (cluster B). The lactic acid concentration increased after twelve (12) hours of process, reaching 6278,08 mg/L and 4435,6 mg/L for Caturra and Castillo, respectively. The glucose concentration decreased with time since 7089,1 and 7025 mg/L to 2158,56 and 2766 mg/L for Caturra and Castillo respectively. No significant differences in the final coffee quality were found.