Background: Antibiotics are often used to treat hidradenitis, but only topical clindamycin has been shown to be effective in a randomized controlled trial. The paucity of these trials may be the result of difficulties in disease assessment. Objective: We compare topical clindamycin with systemic tetracycline in the treatment of hidradenitis suppurativa, and study clinical disease assessment. Methods: A total of 46 patients with stage 1 or 2 hidradenitis suppurativa were treated in a double-blind, double dummy controlled trial. Results: No significant difference was found between the two types of treatment. Patients’ global assessment of disease was significantly worse than physician’s assessment in 3 of 5 evaluations (P = .0096 to .015), but the correlation between patients’ and physicians’ assessments was satisfactory after only one visit (rs = .761 to .895). Soreness was the key factor in patients’ overall assessment of the disease. Conclusion: Systemic therapy with tetracyclines did not show better results than topical therapy with clindamycin. Subjective factors, particularly soreness, appear to be a key factor in patients’ assessment of the disease and should, therefore, be included as an outcome variable in future therapy studies. (J Am Acad Dermatol 1998;39:971-4.)