Net blotch is one of the most important diseases of barley in Tunisia and it frequently causes heavy yield losses. The causal fungal agent is Pyrenophora teres (anamorph: Drechslera teres) with two forms, P. teres f. teres and P. teres f. maculata showing the net type and the spot type symptoms, respectively. In the current study, we characterized the distribution and the severity of the disease in Northern Tunisian areas. It was easy to differentiate the symptoms caused by the two fungal forms (net and spot), but no morphological difference between conidia of these forms was observed. The confirmation of the identity of the fungus was achieved based on molecular techniques, using two specific primers, PTT for the net form and PTM for the spot form.