The radiographic findings in 167 horses subjected to radiography of the facial area, nasal cavity and paranasal sinuses are recorded. Cases were grouped according to clinical diagnosis and the common and disparate radiographic features between and within groups are discussed. Dental disease occurred most frequently and accounted for about 30 per cent of cases, most of which had periapical infection. This disorder presented as two distinct clinical entities in almost equal numbers affected teeth with roots rostral to the maxillary sinus usually produced facial swelling, whereas those with roots within the sinus were generally associated with nasal discharge as a result of secondary sinusitis. In the former group periapical changes could readily be identified on radiographs, but in the latter group affected teeth could be recognised with confidence in only about half the cases. Primary sinusitis was the commonest specific condition recorded and accounted for 32 cases, three of which were mycotic. Using lateral erect projections, comparison of the radiographic features of primary sinusitis and sinusitis secondary to dental disease showed some useful differentiating signs. In four ponies, rhinitis associated with sinusitis led to disruption of the intra-nasal structures but mycotic rhinitis, nasal ulceration and an intra-nasal foreign body produced no radiographic abnormalities. Sixteen cases of suture periostitis were recorded, with varying degrees of new bone formation, and of 13 animals presented for evaluation of trauma, pre-diagnosed fractures were demonstrated in 10 and complications due to sinusitis in three. Twelve cases of paranasal sinus cysts and three of 10 progressive ethmoidal haematomas showed non-specific radiographic changes within the spectrum of those recorded in sinusitis, while the remaining ethmoidal haematomas produced distinctive clearly defined opacities, four of which were within paranasal sinuses. Four tumours were confirmed histologically, but other neoplastic lesions are probably also included in a group of 10 cases of undiagnosed cysts or masses. Other conditions, which occurred sporadically, are of anecdotal interest only. The incidence of wolf teeth among a group of 134 horses was 33 per cent.