An objective of this study was to determine the effect of passive transfer status on morbidity and mortality in neonatal Holstein dairy calves (n = 1,631). Calves, from dairy farms in the western United States, were assigned an individual electronic identification and entered into Feedlot Health Management Services proprietary software system, iFHMS (Preston, ID). Cause-specific morbidity and mortality was recorded on an individual calf basis daily from entry to exiting or death. A 5 mL tube of whole blood was collected from each animal at 48 ± 6h post-arrival. Whole blood was centrifuged at 2000g for 10 min and serum was stored at −22°C until analyzed. Serum total protein (TP) was measured using a digital refractometer (Weaver et al., 2000). Calves were categorized based on proposed USDA serum TP guidelines into poor (TP <5.1 g/dL, n = 159, mean ± SD 4.68 ± 0.31 g/dL), fair (5.1 < TP = 5.7 g/dL, n = 399, 5.45 ± 0.19 g/dL), good (5.8 = TP = 6.1 g/dL, n = 322, 5.96 ± 0.11 g/dL) and excellent (TP >6.1 g/dL, n = 751, 6.90 ± 0.59 g/dL). Data were analyzed using generalized linear mixed model (Proc Glimmix) in SAS with significance declared at P = 0.05. Results showed that there was significant difference between poor and excellent in total respiratory disease treatments as well as the total gastrointestinal disease treatments (P < 0.001 for both). Gastrointestinal and respiratory diseases were defined and diagnosed subjectively on an individual animal basis. A calf treated for respiratory disease may exhibit crust on the nose, mucus in the nostrils, raspy breathing, and failing to drink. In cases of gastrointestinal disease, a calf may exhibit scours, lethargy, and dehydration. In addition, there were differences in the ear disease treatments in relation to serum total protein status (poor vs excellent and fair vs excellent; P < 0.01). Higher morbidity was demonstrated in calves with lower serum TP values measured within the first few weeks of life, suggesting that other factors affecting immunity and overall health, such as lipid soluble vitamins, may be involved, which warrants further investigation.