Description: The diagnostics of porcine respiratory disease complex (PRDC) requires a complex investigation with compulsory use of a serological assay (enzyme-linked immunosorbent assay, ELISA). The polymerase chain reaction (PCR) assay is also becoming more and more important. Prevention plays an essential role for eradication of this disease complex. The treatment with antibiotics is less important. The control measures should be complex and are mainly focused on restriction and hygiene. They include parent herdsТ closure, schedules for early weaning of piglets (segregated or medicated early weaning), the all-in/all-out management technology, periodical serological surveys etc. Vaccinations result in relatively weak effect against the main PRDC agents. The use of live vaccines in PRRSV interferes with the diagnostics and generates a risk of virulentization of the vaccinal strain whereas killed vaccines are not sufficiently immuнnoнgenic and therefore also impede diagnostics. The weak immunity in Mycoplasma infections is mainly due to the epithelial localization of pathogens, that makes them hardly accessible for host immune defense. The non-specific prevention is also prevailing for control of other bacterial agents of PRDC