The following HCEA Top 50 medical meeting list was compiled based on all reported healthcare conventions reported to the Healthcare Convention and Exhibitors Association (HCEA) taking place in 2009 in the United States.

Ranking Criteria
The top 50 largest medical meetings are ranked by total reported attendance, which is all registered participants at a convention, including exhibitors. In the case of a tie, professional attendance is used to further determine the rank. These meetings are reported for 2009 and include both actual and estimated attendance figures. This is self-reported information provided by the event organizers.

HCEA is a not-for-profit organization representing healthcare convention and exhibition organizers and healthcare exhibitors. HCEA has been collecting medical convention and exhibition data for over 50 years and maintains the world’s largest repository of healthcare convention and exhibit data.

Rank	Association Name	Attend Total	Attend Prof.
1	Greater New York Dental Meeting	59,166	37,206
2	Radiological Society Of North America, Inc.	56,824	26,363
3	American Academy Of Orthopaedic Surgeons	33,440	17,624
4	American Dental Association	32,000	20,000
5	Chicago Dental Society	31,333	16,644
6	Society For Neuroscience	30,581	25,794
7	FIME Intermed USA	30,306	n/a
8	American Society Of Clinical Oncology - Annual Meeting	29,600	23,500
9	Healthcare Information & Management Systems Society	27,627	12,766
10	Massachusetts Dental Society - Yankee Dental Congress	26,138	19,683
11	American Academy Of Ophthalmology	25,617	16,723
12	California Dental Association - Anaheim	25,535	20,532
13	Hinman Dental Society	21,426	17,000
14	American Society Of Hematology	21,266	n/a
15	American Heart Association: Scientific Sessions	20,946	15,913
16	American College Of Cardiology	20,709	14,839
17	American Society Of Health System Pharmacists - Midyear Clinical Meeting And Exhibition	20,065	15,049
18	Pittsburgh Conference On Analytical Chemistry & Applied Spectroscopy	19,018	11,375
19	American Association For Clinical Chemistry	17,638	9,774
20	California Dental Association - San Francisco	16,123	11,476
21	American Society Of Anesthesiologists	15,735	9,912
22	American Association Of Orthodontists	15,396	9,389
23	Digestive Disease Week	15,273	n/a
24	American Association For Cancer Research	15,131	10,282
25	American College Of Rheumatology	14,797	11,443
26	Institute Of Food Technologists	14,565	8,755
27	Biotechnology Industry Organization - International Convention & Exhibition	14,352	14,352
28	North American Veterinary Conference	14,036	7,970
29	National Safety Council Congress & Expo	14,000	10,000
30	American Thoracic Society - International Conference	13,824	11,862
31	American Diabetes Association	13,107	13,107
32	Western Veterinary Conference	13,003	7,984
33	American Public Health Association	13,000	10,750
34	Heart Rhythm Society - Scientific Session	13,000	8,000
35	American Society Of Nephrology - Renal Week	12,689	9,944
36	TCT: Transcatheter Cardiovascular Therapeutics	11,779	5,889
37	Association Of Perioperative Registered Nurses	11,250	5,672
38	American College Of Obstetricians & Gynecologists	11,000	3,660
39	Experimental Biology	10,742	8,533
40	Pri-Med - West	10,500	8,000
41	American Psychological Association	10,285	7,575
42	American College Of Emergency Physicians - Scientific Assembly	10,010	5,997
43	American Dietetic Association	10,000	8,500
44	Pri-Med - East	10,000	7,150
45	American Academy Of Family Physicians	9,913	4,231
46	National Athletic Trainers' Association	9,700	7,000
47	Interscience Conference On Antimicrobial Agents & Chemotherapy	9,591	8,130
48	American Veterinary Medical Association	9,488	5,588
49	American Academy Of Otolaryngology - Head & Neck Surgery Foundation	8,602	5,505
50	San Antonio Breast Cancer Symposium	8,493	n/a