Seventy patients received loratadine 40 mg once daily, terfenadine 60 mg twice daily, or placebo in a 14-day, double-blind, randomized study. Four nasal and four non-nasal symptoms associated with allergic rhinitis were evaluated. At the endpoint (the last evaluable visit), the mean total scores of combined nasal and non-nasal symptoms decreased (improved) from the baseline by 51.8% and 55.7% with loratadine and terfenadine, respectively, but increased (worsened) by 6.1% with placebo. There was a significant difference between both the loratadine and terfenadine treatment groups and the placebo group (P = 0.001) but not between the active medication groups (P = 0.608). Overall therapeutic response was good or excellent in 14 of the 23 patients given loratadine, in 18 of the 24 given terfenadine and in none of the 23 given placebo. The difference between each active medication group and the placebo group was significant (P less than or equal to 0.01) but there was no significant difference between the two active treatment groups (P greater than 0.35). No loratadine patient had any adverse side-effects. Sedating effects occurred in one terfenadine patient, headache in one placebo patient and two terfenadine patients (one terfenadine patient with severe headache discontinued treatment), and dyspepsia in two placebo patients. No anti-cholinergic effects occurred in this study. Loratadine 40 mg once daily was effective and safe in the relief of symptoms of allergic rhinitis.