Pre-slaughter transportation may affect poultry welfare and mortality rates. A retrospective analysis was conducted to examine the effect of environmental, management and individual factors on the percentage of dead birds during pre-slaughter transportation (dead-on-arrival, DOA). The variables accounted for in the analyses included: environmental temperature, travel duration, genetic line, gender, crate type and crate stocking density. Among the 41 452 loads of turkeys (34 696 388 birds) and 3241 of end of lay hens (21 788 124 birds) transported to three large abattoirs in northern Italy in a 3-year period, the median DOA was 0.14% in turkeys, and 0.38% in hens. In turkeys, travel duration longer than 30 min, temperature higher than 26°C and high in-crate densities were associated with increased DOA. In winter (⩽2°C), high stocking densities did not reduce the mortality risk from cold stress; on the contrary, for stocking densities either near to or just above the maximum density in EC Reg. 1/2005, the DOA risk was greater than for loads with densities of 10 kg/m2 less than the EC maximum. Male birds and specific genetic lines also showed a higher DOA. In hens, transportation lasting longer than 2 h and the brown-feathered breed were associated with higher DOA. Dead-on-arrival progressively increased with travel duration, remaining constant between 4 and 6 h and peaking at 8 h (median: 0.57%). The maximum DOA increase was detected during winter. These results show that several species-specific factors may lead to increased risk of mortality.