The cytopathologic findings in 17 patients with hydatid cyst are reported. All patients but one were referred for evaluation of a tumor mass. In 13 patients the aspirated material was diagnostic of hydatid cyst. In four patients only acellular laminated membranes were present in the aspirate and a presumptive cytopathologic diagnosis of hydatid cyst was made. Subsequent histologic studies confirmed the diagnosis of hydatidosis in all patients. No complications were encountered. Fine-needle biopsy appears a safe diagnostic approach in the evaluation of suspected hydatid disease. The presence of acellular laminated membranes confirm the diagnosis of hydatid cyst.