Improvements in cow comfort through changes in barn type could impact milk yield (MY) and income over feed costs (IOFC). We conducted a case study analysis in a commercial dairy farm of Argentina (Chiavassa Dairy Farm; −32°02′60″ S, −61°47′59″ W) with the objective to investigate the effect of barn type on MY and IOFC: open lot (OL) vs. compost bedded pack (CBP). We analyzed daily MY data from one barn of primiparous cows (lactation = 1) and one barn of multiparous cows (lactation ≥2) during a 6-yr period from June 1, 2012, until July 17, 2017. Barn type changed from OL to CPB barns on January 24, 2014. Primiparous’ barn held (mean ± SE) 329 ± 23 and 214 ± 35 SE cows from 0 to 105 DIM at a cow stock density (CSD) of 24.4 ± 2.0 and 15.8 ± 2.5 m²/cow before and after January 24, 2014. Multiparous’ barn held 249 ± 16 and 193 ± 31 cows from 0 to 150 DIM at a CSD of 29.0 ± 1.9 and 17.6 ± 2.9 m²/cow before and after January 24, 2014. Analysis included a 601-d data set when cows were housed in OL (June 1, 2012 to January 23, 2014) and a 1270-d data set when cows were housed in CBP (January 24, 2014 to July 17, 2017). The effect of barn type (OL vs. CBP) on MY was analyzed using a repeated-measures ANOVA design (InfoStat, 2017) with DIM and year as covariate. For both primiparous and multiparous cows, the effect of covariates were significant (P < 0.05); year probably accounted for the genetic progress. When corrected for covariate variable, the effect of barn type on MY was significant (P < 0.05). Primiparous cows in CBP yielded 1.21 kg/d more milk than in OL (34.11 ± 0.12 vs. 32.90 ± 0.22). Multiparous cows in CBP yielded 7.37 kg/d more milk than in OL (43.09 ± 0.20 vs. 35.72 ± 0.39). Estimation of IOFC was done using DMI and feed cost data of primiparous and multiparous cows measured during a 12-mo period (July 2016 to June 2017). Farm-gate milk price and feed cost (DM basis) averaged US$0.303 and 0.164 /kg, respectively. The higher MY with CPB increased IOFC from US$6.27 to 6.64/d for primiparous cows and from US$6.63 to 8.86/d for multiparous cows. Our data show that significant improvements in MY and IOFC are possible if cow comfort is improved with better barn facilities.