It is truly difficult to adequately acknowledge the many contributions - samples, microphotographs, suggestions - that were made by so many of our colleagues and friends so that we could complete this Atlas of Human Intestinal Protozoa. We wish to express our gratitude to Marco Albonico, Alessandra Arzese, Francesco Bernieri, Juan Carlos Casanova, Ettore De Canale, Ninoska Donnarumma, Simona Gatti, Giuseppe Giocoli, Maurizio Gulletta, Jose Manuel Hernandez, Jay Keystone, Achille Parilla, Daniele Parilla, Maurizio Pea, Manuela Pegoraro, Faustino Torrico, and Vincenzo Villanacci.

Zeno Bisoffi, director of the Tropical Diseases Laboratory at the Sacro Cuore Hospital in Negrar (VR), is thanked for providing access to the laboratory and to samples from many countries. We also thank the laboratory personnel for their gracious collaboration: Monica Degani, Maria Gobbo, Manuela Mistretta, Maria Santacatterina, Tiziana Serafini and Stefano Tais. We are indebted to Mariella Anselmi, director of the "Centro de Epidemiologia Comunitaria y Medicina Tropical" (CECOMET) of Esmeraldas, Ecuador, and to her collaborators Rosanna Prandi, Gregorio Villacis Montalvo, Juan Moreira and Francisco Robinson for collecting samples. The Ecuadorian Ministry of Health is acknowledged for authorizing the shipment of these samples to Italy.

Paolo Fontana, head of the Laboratory of Pathology and Anatomy at the Hospital of Desenzano del Garda (BS), and his coworker Anna Biral are thanked for sharing their competence and experience in permanent staining techniques

A warm thanks goes to Gino De Marchi (DDK Italia) who generously provided many of the staining reagents and to Gianfranco Zarantonello and staff - particularly Claudio Castro - of AZ Color for the graphical suggestion.

We are indebted to bioMérieux Italia for producing the CD-ROM version of the Atlas of Human Intestinal Protozoa.

To anyone whose contribution has inadvertently been omitted, we apologize and thank you with the same sincere gratitude.

Finally, we wish to make a particular tribute to Professors L. R. Ash and T. C. Orihel. To these known and esteemed parasitologists, we express our deep gratitude for having provided us precious advice and, especially, for having passionately dedicated their entire professional lives to the teaching of parasitology.