The efficacy of a new administration form of oxymetazoline, a nasal bellows container, was investigated in two separate studies by means of a combined treatment with phenoxymethyl-penicillin for acute maxillary sinusitis. In the first study (study 1), oxymetazoline administered with a bellows (OXBE) was compared both with a placebo belows (PLBE) as well as with oxymetazoline and placebo administered with a conventional nasal spray (OXSP respective PLSP) in 73 patients. In the second study (study 2), OXBE was compared only with PLBE in 48 patients. Objective evaluation was made by comparing the radiographical improvement in conventional plain sinus X-ray images. A scoring system corresponding to the outcome of antral irrigation was used for evaluating the X-ray pictures. Subjective symptoms; nasal stuffiness and pain, were assessed by registrations on visual analogue scales. Neither with regard to radiographical improvement nor to decrease in subjective symptoms could any significant differences be found between the different treatment modes. Oxymetazoline administered with a nasal bellows thus did not accelerate the rate of healing of acute maxillary sinusitis in these two studies. It is inferred from these results that decongestion of the sinus ostia is not of primary importance for the course of healing of a manifest acute sinusitis.