Prevalence of the mechanical harvesting brought about significant changes in the conventional production processes in Turkey especially from the point of row spacing and variety. These changes in the production process increased the importance of picker performance from the point of field operation (quantitative) and effect to the lint quality (qualitative). The studies on the effect of the row spacing on the picker performance were usually concentrated on qualitative parameters. However, the amount of harvested cotton (and thus losses) and field performances of the pickers are quite important in Turkish conditions because the trading is based on seed cotton in contrast to the other countries. The objective of this study was to determine the effect of variety and row spacing on the quantitative and qualitative performances of a narrow row, self propelled cotton picker widely used in Turkey. The study was conducted in the field of 8 ha (328 m long), according to split-plot experimental design. Two varieties, Carmen and Stoneville 373 were planted at 76 and 81 cm row spacing. Defoliation was performed by ground sprayer 20 days before harvest by using mixture of 480 g/l ethephon+60 g/l cyclanilide (Finish) and 120 g/l thidiazuron+60 g/l diuron (Dropp Ultra) at application rates 2.5 and 0.4 kg.ha(-1), respectively, with volume of approximately 500 litres per ha. CASE-IH, Cotton Express 420 model, five narrow row mechanical cotton picker was used for harvesting. Ground loss and stalk loss values were within the proposed limits as indicated by the national standards. Results were influenced by variety and row spacing interactions significantly. Lower values were obtained at Carmen-76 cm and St373-81 cm plots comparing with the other plots. No significant relationships were found between harvestable boll ratio, yield and losses. No significant relationship between treatments and the other qualitative parameters was found except for micronaire. Depending on the trash content, there was a decrease in the reflectance (Rd) values of the machine picked samples in comparison to the hand picked samples, and an increase in yellowness (+b) values. In both varieties, the low defoliation ratios caused an increase in trash content and a decrease in the degree of color. The fundamental indication of the measured values was that the success of the defoliation process significantly influenced the lint quality values.