This study examines the effect of NaOH treatment on the nutritive value of Pima cottonseed for lactating cows. Treatment of Pima cottonseed with NaOH increased the extent of dry matter (DM) and neutral detergent fiber in vitro digestibility. Three groups of cows were fed 3 similar total mixed rations (TMR) differing only in the type of cottonseed fed, either whole linted Akala, whole unlinted Pima, or whole Pima treated with 4% NaOH (T-Pima). Dry matter and organic matter (OM) intakes of Akala and Pima TMR were similar and tended to be lower compared with cows fed T-Pima. This was reflected in similar intake of crude protein and lipids by cows fed the 3 TMR. Digestibility of DM, OM, and crude protein were similar in cows fed Pima and T-Pima diets, and slightly higher in cows fed the Akala TMR. Lipid digestibility was highest in cows fed Akala TMR, whereas cellulose and NDF digestibility were lowest in Pima TMR. In the 3 TMR, there was a large gap between the high values of "digestibility of intact seeds" and actual in vivo digestion of DM and OM. Similar yields of milk and milk protein were obtained in cows fed the Akala and Pima TMR, whereas higher yields of milk, milk protein, milk fat, and 4% fat-corrected milk were found in the T-Pima cows. Similar efficiency of DM intake for fat-corrected milk production was achieved by cows fed the 3 TMR.