Exhibit 31 		Certifications Under Rule 13a-14(a)/l5d-14(a) 	I, Henry C. Pao, certify that: 	1.	I have reviewed this quarterly report on Form 10-Q of Supertex, 	Inc., a California corporation; 	2.	Based on my knowledge, this quarterly report does not contain 	any untrue statement of a material fact or omit to state a material 	fact necessary to make the statements made, in light of the 	circumstances under which such statements were made, not misleading 	with respect to the period covered by this quarterly report; 	3.	Based on my knowledge, the financial statements, and other 	financial information included in this quarterly report, fairly present 	in all material respects the financial condition, results of operations 	and cash flows of the registrant as of, and for, the periods presented 	in this quarterly report; 	4.	I am responsible for establishing and maintaining disclosure 	controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 	15d-15(e)) for the registrant and I have: 		(a)	designed such disclosure controls and procedures, or 		caused such disclosure controls and procedures to be designed 		under my supervision, to ensure that material information 		relating to the registrant, including its consolidated 		subsidiaries, is made known to us by others within those 		entities, particularly during the period in which this 		quarterly report is being prepared; 		(b)	evaluated the effectiveness of the registrant's 		disclosure controls and procedures and presented in this report 		my conclusion about the effectiveness of the disclosure 		controls and procedures, as of the end of the period covered by 		this report based on such evaluation; and 		(c)	disclosed in this report any change in the registrant's 		internal control over financial reporting that occurred during 		the registrant's most recent fiscal quarter that has 		materially affected, or is reasonably likely to materially 		affect, the registrant's internal control over financial 		reporting; and 	5.	I have disclosed, based on my most recent evaluation of 	internal control over financial reporting, to the registrant's auditors 	and the audit committee of registrant's board of directors (or persons 	performing the equivalent function): 		(a)	all significant deficiencies and material weaknesses in 		the design or operation of internal control over financial 		reporting which are reasonably likely to adversely affect the 		registrant's ability to record, process, summarize, and report 		financial data and have identified for the registrant's 		auditors any material weaknesses in internal controls; and 		(b)	any fraud, whether or not material, that involves 		management or other employees who have a significant role in 		the registrant's internal control over financial reporting. 	Date: November 7, 2003 				/s/ Henry C. Pao 				--------------------------- 				Henry C. Pao, Ph.D. 				Chief Executive Officer and 				Chief Financial Officer 				(Principal Executive and Financial Officer)