Abstract This study assessed the effects of RYR1 mutation on the health, welfare, and carcass and meat quality in slaughter pigs. Any signs of pneumonia, pleurisy, pericarditis, and liver milk spots were recorded as present or absent. At exsanguination, blood samples were collected and RYR1 genotype, blood lactate and glucose concentrations were determined. The following carcass quality traits were measured: live, hot and cold carcass weights, backfat thickness, loin muscle thickness, lean meat content and skin lesion score. pH and temperature of M. longissimus dorsi and M. semimembranosus were measured 45 minutes postmortem. Nn pigs were more affected by pneumonia, had higher blood lactate and glucose concentrations and more developed rigor mortis than NN pigs. NN pigs had lower daily weight gain, produced lighter carcasses, more fat and less meat than Nn pigs. Meat obtained from Nn pigs was of a lower quality class than meat obtained from NN pigs, as shown by the lower pH and higher temperatures measured 45 minutes post mortem in both muscles and higher prevalence of pale, soft and exudative meat. In conclusion, the presence of a mutant n allele in pigs positively affected carcass quality traits, but had a deleterious effect on health, welfare and meat quality.