The acute porphyrias constitute a group of metabolic disorders engaging enzymes 
in the haem synthetic chain and generally following dominant inheritance 
patterns. Some gene carriers are vulnerable to a range of exogenous and 
endogenous factors, which may trigger neuropsychiatric symptoms. Early diagnosis 
is of prime importance since it makes way for counselling with the aim to block 
the development of acute, as well as late, disease. The medical and 
psycho-social consequences of a porphyria diagnosis are considerable and the 
freedom for maldiagnosis correspondingly small. The strain imposed upon the 
diagnostic process makes management in specialized laboratories necessary. 
Inadvertent handling of the diagnostic procedures in laboratories lacking in 
knowledge, experience and technical competence is repeatedly the reason for 
harmful underdiagnosis and overdiagnosis. Gene diagnosis of the carrier 
condition, principally within reach in all types of acute porphyria, is of 
incomparable versatility and accuracy. However, despite recent great 
achievements in the molecular biology of porphyric disease, genomic procedures 
cannot replace biochemical methods in monitoring the activity and progress of 
the disease, or the effects of therapy. The classical methods are also useful 
when it comes to screening for the associated disease states. In these tasks, 
professional handling of the methods and skillful interpretation of the results 
are of paramount importance. Knowledge of the limitations and pitfalls of the 
procedures is a guard against maldiagnosis, which may be fatal. In the article 
the main diagnostic challenges are discussed; the strategy for early detection 
of the gene carrier state, the recognition and surveillance of the acute 
porphyric crisis, the evaluation of subacute/subchronic symptoms, the 
differential diagnoses of the cutaneous porphyrias and the monitoring of late 
complications.